In this paper a new approach，named Equivalent Capacity，is introduced to set up a GIS-based evaluation system of Urban Expressway，including methodology，criterion and framework．Then，the function and structure of this GIS-based evaluation system are explicitly outlined．Finally．an appfication of this evaluation system in Shanghai is presented．In this paper a new approach，named Equivalent Capacity，is introduced to set up a GIS-based evaluation system of Urban Expressway，including methodology，criterion and framework．Then，the function and structure of this GIS-based evaluation system are explicitly outlined．Finally．an appfication of this evaluation system in Shanghai is presented．