The corrugated web is used instead of the straight web to obtain the larger out-of-plane stiffness with fewer stiffeners and thinner web for composite girders. Aimed to study the failure mode and stress characteristics of composite steel plate girder with corrugated webs, the bending test was carried out, and the finite element models were established and verified. The calculation methods of yield load and ultimate flexural capacity of composite steel plate girders with corrugated webs were deduced. The parametric analysis of concrete slab thickness, flange thickness, flange width, corrugated web height, and span on the flexural performance of composite steel plate girders with corrugated webs were conducted by the multi-scaled finite element models. The results show that the bending performance of composite steel plate girders with corrugated webs conforms to the “quasi-planar section assumption.” The yield load and ultimate load of composite steel plate girders with corrugated webs are significantly improved with the increase of the thickness of concrete slab thickness, bottom flange thickness, and corrugated web height. The fitting degree between the results of yield load and ultimate flexural capacity obtained by the test and proposed calculation method are 98.5% and 101.3%, respectively.