Abstract: The seismic hazard of sites must be evaluated and aseismatic design must be adopted for structures before projects are constructed. It is difficult for engineers to choose the appropriate acceleration of earthquake-resistance for projects safely and economically in actual application. This is because only a scope of acceleration of earthquake-resistance or earthquake intensity is provided for a region by relevant departments in China. Additionally, the range of acceleration corresponding to an earthquake intensity is very large. In order to solve the problem, a seismic hazard assessment system is developed based on the probability seismic hazard assessment theory. The acceleration of earthquake-resistance for projects can be calculated conveniently and quickly using the assessment system developed according to correlative earthquake activity parameters. Consequently, the problem of choosing the acceleration of earthquake-resistance safely and economically can be solved well. In this paper, an accurate solving algorithm and an approximate solving algorithm are given respectively toward the problems of a line-source and an area-source. The two sources have difficulties to be handled in programming. Some assessment calculations are given with examples. The calculation results are consistent with these data promulgated by China Earthquake Administration (CEA). Therefore, the reliability of the system developed in this paper is proved to be good to some extent.