The existing heavy-haul railway concrete simply supported double-T-type beam bridges can not meet the requirements of heavy haul transport. So, a strengthening method of bonding assisted steel beams for the existing heavy-haul railway bridges was put forward. Using the theory of train-track-bridge time-varying system, the spatial dynamic analysis model of train-track-bridge system was set up. And based on the existing heavy-haul railway concrete simply supported double-T-type beam bridge and strengthening method, the dynamic response was analyzed, the dynamic response of bridges at different speed reinforcements was calculated. Comparing the real vehicle testing data with the calculation results, it has been shown that the strengthening method of bonding assisted steel beams can improve the lateral and vertical stiffness of the concrete simply supported double-T-type beam bridge. Therefore, the strengthening method is feasible and reasonable.