WMS 请求透明背景的图层

TRANSPARENT

只需添加 URI 查询参数TRANSPARENT=true即可:

http://localhost:8080/geoserver/ttt/wms?service=WMS&version=1.1.0&request=GetMap&layers=ttt%3Ahello_shp&bbox=-140.661117553711%2C34.8622970581055%2C-92.1056976318359%2C59.1777877807617&width=768&height=384&srs=EPSG%3A4326&format=image%2Fpng&TRANSPARENT=true

see https://support.esri.com/zh-cn/technical-article/000019016