The transverse strengthening method of T-girder bridge is in introduced. Combined with a bridge strengthening case of Wuhan, the application of the transverse strengthening method how to change the flange pin joint of old T-girder bridge to rigid joint, how to strengthen the diaphragm and how to add the pre-stressed crossgirder, and the strengthening effects are introduced in details, which can be referred for strengthening the similar T-girder bridges.