static void Main(string[] args) { string ExecuteDesc = "所要插入的字符串"; int count = ExecuteDesc.Length / 20; for (int j = 1; j <= count; j++) { ExecuteDesc = j == 1 ? ExecuteDesc.Insert(j * 20, "<br/>") : ExecuteDesc.Insert(j * 20 + (j - 1) * 5, "<br/>"); } }