Intelligent Substation Power Dedicated Switch accumulates SV forwarding delay and link transmission delay step by step, and marks in SV message,To solve the intelligent substation SV point to point transmission,Can not network to achieve data sharing. The performance of the switch was tested in detail, Combined with the intelligent substation system in the stable operating conditions, respectively, under the extreme conditions of avalanche power system reliability test. Use a dedicated network tester closed-loop test method, Protection device phase calculation method to test SV mark delay accuracy, And the data were analyzed in detail, To guide product development and engineering applications provide a basis.