Abstract: The deposition is controlled by structure controls. The depositional models are different under different structure back-ground. Xisha Trough was formed in the Central Depression of Qiongdongnan Basin due to the intensive tectonic subsidence in the late Miocene. Because of the special regional structure backgrounds in the surroundings, the water from Red River flowed into Xisha Trough from northwest, and fluvial system developed along bottom of Xisha Trough. The slope styles of Xisha Trough was control-led by source supplying rate. Xisha Trough Depositional Model consisted of fluvial system at trough bottom, suspended depositional system in the upper part of north slope of the trough, turbidite and slump system in in the lower part of north slope of the trough.