Abstract: The montanic long-span suspension bridge abuilding is taken as an example, the iterative fitting method which is compatible with design response spectrum is adopted to respectively simulate the uniform excitation, wave passage effect and multi-point excitation, which are in turn used as the earthquake ground motions input for the suspension bridge. According to two-phase aseismic fortification criterion, linear and nonlinear seismic time-history analyses are carried out under two kinds of combinations of earthquake ground motion inputs, i.e., the longitudinal & vertical directions and the lateral & vertical directions, the peak bending moment and shearing force distributions of the main tower are calculated. The analysis shows that the multi-support excitation effect affects greatly in the longitudinal bridge direction while the result of three cases is almost the same in the lateral bridge direction, and calculation results of the linear and nonlinear analyses are very close.