In order to analyze the error source of seismic parameters of PSD model and its sensitivity influence on ground varying motions and seismic response of long-span Bridge, two methods (direct and integral method)that usually used to solve the parameters in target PSD model according to CRS are briefly reviewed. Then, a visualization program named TJU.SPSP was developed and the main parameter values of PSD were listed in fixed format. Base on the results, the fundamental error source that caused by different methods were analyzed obviously. Moreover, the program for multi-point earthquake motions simulation (MEMS_b) was updated and the relationship between earthquake-induced ground motion energy and site soil type were summarized. The results indicate that the two methods have significant influence on the amplitude and band width of dominant frequency. The parameters describing the low-frequency component in PSD models are important and can't be ignored. Furthermore, the physical and mathematical significance of damping ratio in PSD models were clarified. Finally the validity of the theoretical analysis was verified by analyzing the seismic responses of a real long-span bridge.