In considering of the site conditions and source parameters, this article starts from synthesis of the earthquake ground motion, and synthesizes the accelerograms on bedrock at some specified points by stochastic finite faults method, then researches the strong ground motion coherence among these points. It proves that the coherency model on bedrock is of rationality through comparing the synthesis results. Meanwhile, it is known that the accelerograms simulated by stochastic finite fault method can be used as the multi-point input for high-rise structures, long-span bridge and other key engineering structural aseismic analysis.