For the reasons of prestressing and other factors, the lateral bending would appear on the post-tensioned concrete T-beam during the pre-tensioning. In this paper, a simulation model is established as an example of the edge beam of 40-m T-beam which is widely used. According to the stress and displacement of main girder under different orthogonal force, the effects of lateral bending on the main girder are analyzed. Finally, some guidelines are suggested.