In this study, we used the dynamic time history method to analyze the seismic response of bridge structures. The time history analysis method, which has higher accuracy than the response spectrum method, can identify various kinds of responses and can also consider various factors in the calculation and analysis, including the coherent effects, multi-dimensional inputs, and multi-dimensional responses. The primary problem in applying the dynamic time history method is how to simulate ground motion acceleration. In the artificial acceleration wave, the velocity and displacement of the seismic wave deviate from the baseline. At the end of the seismic wave, the velocity and displacement time history are not zero, which generates a baseline drift of the seismic wave. As such, it is necessary to revise the seismic response before analysis and to eliminate the influence of the baseline drift phenomenon. At the same time, the response spectrum of the acceleration wave before and after correction must be checked and compared. In this paper, based on a 2D coherent model, we analyze the seismic response of a wide long-span bridge structure under multi-point excitations of a random earthquake motion field. We use the polynomial fitting method to adjust them in the time domain. We use the response spectrum to check the seismic wave, which is corrected before and afterwards. Then, taking a large-span self-anchored suspension bridge as an example, we use the linear time history analysis module in the finite element analysis software and the synthetic seismic wave to analyze and compare the seismic response results under uniform and multi-point excitations. The results indicate that the artificial acceleration wave must take into account the baseline drift phenomenon, and the polynomial fitting method can be used to adjust the waves. In addition, the seismic waves corrected before and after must be checked against the response spectrum. For large-span and wide bridge structures, the non-uniformity of transverse seismic waves must be taken into account.