In order to reasonably determine the importance of the factors affecting the overall earthquake damage of buildings during the on-site safety evaluation after earthquake, Analytic Hierarchy Process（AHP）is used to investigate the weight coefficients of the factors. The calculation procedure of AHP method was introduced in detail, and the weight of each influencing factor of earthquake damage of single-story reinforced concrete column workshop was calculated by example. It is shown that AHP method is simple and accurate. When AHP is used to deal with complex system problems, the influence of each influencing factor is quantifiable and very clear. AHP method can combine qualitative method and quantitative method organically to decompose complex system. It is concluded that the AHP method is very reasonable and accurate to determine the weight coefficients of the factors affecting the earthquake damage of single-story reinforced concrete column workshop. Therefore, AHP method can also be used as a reference when determining the weight coefficients of the influencing factors of the overall seismic loss of other types of structures.