About tms Transparency

what can i do,the first is transparency in cesium , but second is not transparency in cesiunForUnreal

I would expect TMS transparency to work in Cesium for Unreal. Can you tell us more about your setup? In particular, have you assigned the two raster overlays different MaterialLayerKey values? The bottom should be Overlay0 and the top Overlay1. Also, are you using a custom Material, or are you using the default?

The bottom is staticMesh include some buildings or roads or tree.not TMS layer.

other setting is default

So the buildings and roads are not a Cesium3DTileset at all? In that case, what sort of tileset is the TMS raster overlay attached to?