The invention provides an energy saving evaluation system and method for power supply and distribution networks of industrial enterprises. The evaluation system comprises a plurality of RS485 electric energy meters used for conducting sampling, a plurality of RS485 buses, a plurality of ZigBee wireless networks, the Ethernet, an electric power data collection computer and a power supply and distribution energy saving evaluation computer. Collected data are transmitted to the electric power data collection computer by the RS485 electric meters through the RS485 buses, the ZigBee wireless networks and the Ethernet and calculated by the electric power data collection computer, the calculation result is transmitted to the power supply and distribution energy saving evaluation computer. The evaluation method mainly includes the steps of setting up an index system and judge levels, setting index sample values, training a CPN model, and evaluating the energy saving level through the trained CPN model after grading is conducted through experts and the computers. The evaluation system is simple in structure, convenient to obtain and low in cost, the evaluation method is reasonable and rapid, the evaluation result is high in reliability, related factors which can affect energy saving of the power supply and distribution networks can be effectively analyzed, and the evaluation system and method can assist the enterprises in energy saving and efficiency improvement.