The evolution of multi- stage paleostress field has controlled the migration of paleouplift and the formation of fracture- karst reservoir since the Triassic in the western Sichuan depression, which plays an important role in controlling the accumulation of oil and gas in this area. However, the quantitative evaluation of the paleostress field in this area is weak at present. Based on field outcrops, drilling cores, thin sections and fracture fillings, this study focused on the paleostress direction, magnitude and evolution stage of the Leikoupo Formation in the later depositional stage of the Pengzhou area of the western Sichuan depression. The results show that there are four periods of stress in this area. The stress direction in the Indosinian period is NW; the stress direction in the early and middle Yanshan is SN; the stress direction in the late Yanshan period is the NW; the Himalayan period is near EW. The corresponding maximum horizontal stress values are 25. 81 MPa, 66. 03 MPa, 41. 27 MPa and 50. 85 MPa, respectively. Combined with the tectonic evolution in the Pengzhou area, the gentle uplift of the Indosinian period resulted in the formation of the paleouplift and the Pengxian fault. The exposed surface of the Leikoupo Formation formed karst reservoirs, which became the subsequent oil and gas enrichment space and migration channel. Under the control of the two phases of Yanshanian stress, the strata in the northern part of the study area were uplifted first, and the paleouplift continued to develop. The strong tectonic compression in the Himalayan period uplifted the NW- trending strata in the whole area, the paleouplift was finally shaped, and the fractures and faults formed played a key role in the adjustment of early oil and gas migration.