Abstract: On the basis of systematic analysis of outcrops, well cores, log and seismic stratigraphy, the stratigraphic sequence of the Middle Jurassic in northern Chaoshui basin was divided into 4 third-order sequences and 2 second-order sequences. According to depositional system and sedimentary evolution analysis, it was indicated that the prevenance changed rapidly and the sedimentary style varied from one thirdorder sequence to another, The variation of prevenance with time reflected tectonic control.