In order to reveal the torsional action mechanism of PC composite box girder with corrugated steel webs, the section torque distribution and torsional deformation compatibility condition were analyzed according to the thin-walled structure theory. The USTMT model was used to calculate the whole torsional process of PC composite box girders with corrugated steel webs. Based on this model, the concrete compressive strength, the thickness and yield strength of corrugated steel webs, the initial force of prestressed tendons, and the strength ratio of the reinforcement were analyzed. The results show that it is reasonable to take the same torsional curvature of concrete slab and steel web as the deformation compatibility condition in PC composite box girders with corrugated steel webs. The cracking torque, yield torque and ultimate torque develop with the increase of the concrete cube compressive strength, but the torque carried by corrugated steel webs is almost unchanged. The thickness of corrugated steel webs has little effect on the torque carried by concrete slabs, but increases the torque carried by corrugated steel webs. The yield strength f_wy of corrugated steel webs has little effect on the cracking torque and the ultimate torque carried by concrete slabs, but it increases the yield torque and the ultimate torque carried by corrugated steel webs. The higher the concrete strength, the higher the strength grade of steel that can make the corrugated steel web yield. The ultimate torque increases with the increase of the ratio of the strength of the reinforcement, and there is a sensitive region to ξ. At the same time, it increases li-nearly with the increase of the initial prestress of the tendons, but the increase rate is small, especially for the torque carried by corrugated steel webs.