Abstract: On the basis of caldera theory integrated with seismic?lithofacies interpretation and tectonic evolution, the paper investigates the structures of Pishan caldera and describes its impact on the Cretaceous reservoirs. It is considered that the large?scaled composite caldera in Pishan formed in the late Hercynian movement, which is a circle with the diameter of 25 km and the maximum subsidence depth of 1.5 km. Volcanic materials erupted in central and fissure mode along the ring fault and the evacuation of magma chamber resulted in sharply subsidence. Volcanic eruption facies, lacustrine facies and Cretaceous breccia facies assume the circular symmetric distribution; innerdipping circular normal faults and outer?dipping circular inverse faults are developed in collapse structure area and high-steep divergent inverse faults occur in central dome structure area, which indicates the complete process of caldera from its first eruption, subsidence to reactivation. Pishan caldera structure controls the development and distribution of the Cretaceous reservoirs