Mishi Basin is located at the junction of the Yangtze Plate and Songpan-Ganzi orogenic belt. Its tectonic characteristics and genesis were studied with the combination of inversion and forward modeling. Affected by the Hercynian movement，the tectonic deformation in the basin was dominated by extensional faults. The Yangtze Plate subducted into Songpan-Ganzi orogenic belt in the Indosinian period，thus the tectonic deformation was dominated by compression and uplift in the basin and the part of the Triassic was denudated. The periphery in the basin continued to uplift in the Yanshanian period，while the internal structure was inherited. The basin entered a stage of rapid compression and uplift in Himalayan period. The typical tectonic characteristics were thrust faults and fault-related folds，and the internal tectonic deformation varied in the basin. The fault-bend deformation constrained by the basement-involved basin-controlling fault was dominant in the east，and the fault detachment deformation controlled by secondary faults was the typical feature in the western margin.The fault development pattern in the basin gradually expanded from the east in the basin to the west. In terms of genesis，from the Hercynian period to the Indosinian period，the basin was continuously compressed by the Yunnan-Qinghai-Tibet oceanic plate and the Pacific Plate，and the earliest Sikai fault was formed inside the basin. The basin appeared in its embryonic form in the Yanshanian period，and the extremely thick Jurassic and Cretaceous were deposited with Qiliba area as the center，with the periphery in the basin continuing to uplift. The basin was compressed by Songpan-Ganzi orogenic belt and Jinpingshan orogenic belt，thus the tectonic pattern in the basin with the coexistence of thrust faults and fault-related folds was formed in the Himalayan period.