In order to analyze the seismic response law of self-anchored suspension bridge, the target response spectrum is determined firstly based on the site feature of bridge. Secondly based on Fourier transform and wavelet function methods, the artificially synthesized seismic motion consistent with the target spectrum is obtained. Finally, the artificially synthesized seismic motion is used as the seismic motion input in the finite element model of suspension bridge. Based on the nonlinear finite element software SAP2000, the nonlinear dynamic time-history response is analyzed. The result shows that the magnitude of the bending moment and shear response at the base of the bridge pylon is related to the number of piers of the adjacent spans. The greater the number of piers, the greater the bending moment and shearing force of bridge pylon (the increase by more than 5%). The displacement response laws at the top of bridge pylon are similar. The magnitude at the extreme value is related to the pier number of the adjacent spans. The maximum displacement value of Pylon 1 with more adjacent piers is 0.44% smaller than that of Pylon 2. That is, the more adjacent piers of the bridge pylon, the greater the internal force response and the smaller the displacement response. The maximum error between the optimized artificial seismic wave response spectrum and the design response spectrum is 9%. The study conclusion provides the reference for the seismic design of long-span suspension bridges.