Vulnerability assessment and vulnerability mapping, is an important strategy to management of karst water resources. Due to the geomorphology of karst developed in karst aquifers and other natural conditions Azhvan-Bisotun area, Emissions are rapidly and widely. The aim of this study is mapping vulnerability Azhvan-Bisotun karst aquifer in Kermanshah province against surface contamination by using COP model. According to the aforementioned approach, the COP method considers three factors to assess the resource vulnerability: Overlying layers (O), Concentration of flow (C) and Precipitation regime (P). The results show that the vulnerability of the area between zero and 4.5, respectively, at the end of the five-class very high, high, medium, low and very low were classified. In general, the total area calculated parameters C, P and O have the most significant role in the vulnerability zone. The results demonstrate that COP is a useful method to assess the vulnerability of the test sites under consideration.