Abstract: The deformation structure and zonation model of piedmont thrust in an intra-continental composite system is an effective method of studying hydrocarbon accumulation regularity. The conjoint analysis of the characteristics of deep geological structures and sedimentary cover in the main piedmont thrust belt, western China indicate that the deformation of the intra-continental piedmont thrust belts is controlled by the different detachments and also by the geometric form and location of the compound land mass. The intra-continental composite piedmont thrust belt is essentially a deformation system formed by an orogenic wedge step sliding along different levels of soft strata from the orogenic wedge to the basin. Four zonation models divide the intra-continental piedmont thrust belt using the depth of main detachment as a key factor combined with deformation style. The models include a thick belt, a transition belt and a thin belt from the orogenic region to the basin, and a transition belt is further divided into transition Ⅰ belt and transition Ⅱ belt. Each belt has its unique characteristics with respect to deformation strata, deformation styles, fault-rupture mechanism, folding styles, fault-related fold principles and geometric theory. The deformation style of the intracontinental thrust belt clearly influences hydrocarbon accumulation regularity. The industrial oil and gas is mainly distributed in the transition zone. During accumulation, oil and gas in transition Ⅰ belt also adjusted, so the present petroleum reservoirs are mainly residual and always in the front part of the belt. Oil and gas in the transition Ⅱ belt mainly accumulated at the late stage and in the center of the belt. Therefore, the key factor for accumulation is the matching style of fault shape and seal. The transition from thick belt to thin belt in the central and western piedmont thrust belt is the key area for seismic technology development and exploration deployment.