首先创建一个自定义控件，在里面定义好treeview的样式，将本来的三角形的图标变为加号的图标，并且添加节点之间的连线。
<UserControl x:Class="TreeViewEx.myTreeView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:i="clr-namespace:TreeViewEx"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
<i:TreeViewLineConverter x:Key="LineConverter"/>
<!-- Toggle Button -->
<Style x:Key="ExpandCollapseToggleStyle" TargetType="ToggleButton">
<Setter Property="Focusable" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid Width="20" Height="18" SnapsToDevicePixels="True">
<Rectangle Width="12" Height="12" Stroke="#919191" SnapsToDevicePixels="true">
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.5,2" StartPoint="0.5,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="Silver" Offset="0.5"/>
<GradientStop Color="LightGray" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="ExpandPath" Width="1" Height="5" Stroke="Black" SnapsToDevicePixels="true"/>
<Rectangle Width="5" Height="1" Stroke="Black" SnapsToDevicePixels="true"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Visibility" TargetName="ExpandPath" Value="Collapsed"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<!-- TreeViewItem -->
<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Padding" Value="1,0,0,0"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TreeViewItem}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="19" Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<!-- Connecting Lines -->
<Rectangle x:Name="HorLn" Margin="9,1,0,0" Height="1" Stroke="#DCDCDC" SnapsToDevicePixels="True"/>
<Rectangle x:Name="VerLn" Width="1" Stroke="#DCDCDC" Margin="0,0,1,0" Grid.RowSpan="2" SnapsToDevicePixels="true" Fill="White"/>
<ToggleButton Margin="-1,0,0,0" x:Name="Expander" Style="{StaticResource ExpandCollapseToggleStyle}" IsChecked="{Binding Path=IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"/>
<Border Name="Bd" Grid.Column="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="True">
<ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" MinWidth="20"/>
</Border>
<ItemsPresenter x:Name="ItemsHost" Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="2"/>
</Grid>
<ControlTemplate.Triggers>
<!-- This trigger changes the connecting lines if the item is the last in the list -->
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource LineConverter}}" Value="true">
<Setter TargetName="VerLn" Property="Height" Value="9"/>
<Setter TargetName="VerLn" Property="VerticalAlignment" Value="Top"/>
</DataTrigger>
<Trigger Property="IsExpanded" Value="false">
<Setter TargetName="ItemsHost" Property="Visibility" Value="Collapsed"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="Expander" Property="Visibility" Value="Hidden"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="HasHeader" Value="false"/>
<Condition Property="Width" Value="Auto"/>
</MultiTrigger.Conditions>
<Setter TargetName="PART_Header" Property="MinWidth" Value="75"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="HasHeader" Value="false"/>
<Condition Property="Height" Value="Auto"/>
</MultiTrigger.Conditions>
<Setter TargetName="PART_Header" Property="MinHeight" Value="19"/>
</MultiTrigger>
<Trigger Property="IsSelected" Value="true">
<Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsSelected" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter TargetName="Bd" Property="Background" Value="Green"/>
<Setter Property="Foreground" Value="White"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid>
<TreeView BorderThickness="0">
<TreeViewItem Header="Program Files">
<TreeViewItem Header="Header"/>
</TreeViewItem>
<TreeViewItem Header="Program Data" IsExpanded="True">
<TreeViewItem Header="Microsoft">
<TreeViewItem Header="Header"/>
</TreeViewItem>
<TreeViewItem Header="Microsoft Help"/>
</TreeViewItem>
<TreeViewItem Header="Uers" IsExpanded="True">
<TreeViewItem Header="Default"/>
<TreeViewItem Header="Public" IsExpanded="True">
<TreeViewItem Header="Libraries"/>
<TreeViewItem Header="Public Desktop"/>
<TreeViewItem Header="Public Documents"/>
</TreeViewItem>
<TreeViewItem Header="TUYEN">
<TreeViewItem Header="Header"/>
</TreeViewItem>
</TreeViewItem>
<TreeViewItem Header="Windows"/>
</TreeView>
</Grid>
</UserControl>
要注意上面的代码中有一句：xmlns:i="clr-namespace:TreeViewEx"，这个TreeViewEx就是这个控件所在的命名空间，在这个控件的后台代码中添加一个类TreeViewLineConverter
class TreeViewLineConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { TreeViewItem item = (TreeViewItem)value; ItemsControl ic = ItemsControl.ItemsControlFromItemContainer(item); return ic.ItemContainerGenerator.IndexFromContainer(item) == ic.Items.Count - 1; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return false; } }
这样控件就做完 了，然后在窗口中引用这个控件，同样的需要在窗体文件中添加xmlns:i="clr-namespace:TreeViewEx"。
<Grid>
<i:myTreeView />
</Grid>