According to the physical circuit model of secondary system in smart substations，this paper proposes a fault location approach is proposed for process level networks based on the proof table.In the approach，information on virtual circuits and physical ports of process level communication is obtained from substation configuration description（SCD）files on smart substations，with sets of channel nodes associated with communication links obtained using topology searching.In addition，the fault proof table for process level channels is established to prove the fault points.According to multiple proof results of channel fault points detection，this approach can be used to locate the process level channel faults with smart substations.