In　this　paper,　in　order　to　solve　the　problem　of　site　zoning　for　urban　district,　which　lack　of　Investigation　data　in　planning　urban　hazardous　prevention,　method　of　estimating　site　category　based　upon　Bayes　theorem　is　adopted　by　means　of　seismic　and　site　information　of　those　sites　that　have　been　classified　and　zoned　in　the　involved　city.　Furthermore,　site　zoning　can　be　gained　by　further　integration　with　the　seismic　geological,　engineering　geological　and　ground　surroundings＇　information.　The　example　of　Quanzhou　city　is　presented　subsequently,　and　basic　procedure　of　site　zoning　by　using　this　method　is　brought　forward,　too.　This　methodology　has　been　applied　in　planning　of　Quanzhou　and　Xiamen　with　good　effect.