The invention provides an intelligent substation process level network transmission performance monitoring method based on FPGA (Field Programmable Gate Array). The method comprises the following steps: a transmitting terminal reserves a flag bit of the message when the MAC (Media Access Control) layer is encapsulated to form frames; a receiving terminal receives the message and issues the message to a cache region of the FPGA; the FPGA checks whether the receiving cache region has the message, if the receiving cache region has the message, the flag bit of the frame is read and the frame is processed; after the message is processed in the FPGA cache region, the message is transmitted to a switching chip. The technical scheme provided by the invention adopts the FPGA manner to acquire the network message performance parameters, control the delay jittering within a protection acceptable determined range (2 ms), and ensure the real time property of the critical service; secondly, the process level network transmission performance monitoring implemented on the switch has the function of identifying the abnormal message transmitted by the access equipment, so as to stop normal forwarding of the corresponding port, not allow the abnormal message to be spread in the network, position the source of the abnormal message, and report warning signals, so that the network reliability is improved.