It is stressed in this paper that the seismic hazard analysis is a complex system with multi-parameters and its parameter sensitivity should be studied as a whole. We have inspected the effects of parameters continuing variation on the result and the effects of exceeding probability and upper bound magnitude of potential source on the parameter sensitivity. Some useful cognitions were got. We have overall calculated the interactions among the parameters including spatial distribution function of earthquake and suggested the concept of relative interaction. The relative interaction is not great than 10% with annual exceeding probability 2 × 10−3. The relative interaction between upper bound magnitude and annual mean rate and the one between upper bound magnitude and space distribution function are 17% and 22% respectively for potantial sources higher upper bound magnitudes in annual exceeding probability 10−4. It is convenient to judge whether considering the interactions in actual application. The importance and necessity of calculating the result of the probabilistic distribution are indicated. The effect of the result distribution by different parameter level weights is analyzed. The whole picture of multi-parameter sensitivity is revealed. It makes necessary preparation for the reasonable uncertainty correction.