Hello , Egon , I'm back .  I use the code as following , but no effect, I can't see any fog. Could you help me? Thanks a lot.
            RGBColor fadeColor = new RGBColor(192, 135, 46);
            world.setFogging(World.FOGGING_ENABLED);
            world.setFogParameters(600, 1000, fadeColor.getRed(), fadeColor.getGreen(), fadeColor.getBlue());
			
			
			
				Should work as long as you scene actually renders stuff that far in the distance... ???
			
			
			
				Thanks,  It's my mistake , I render the skybox cause this problem :P