Abstract: In the deployment scenario where the satellite ground station and the test station are hundreds of kilometers apart, in order to meet the requirements of multi-task in-orbit tests such as ground link index test, satellite in-orbit test, satellite frequency spectrum monitoring during the mission phase, the design of in-orbit test system is improved, and a construction idea of test system based on flexible test network is proposed. An equal amplitude multicarrier group delay measurement method for remote group delay measurement is proposed. The optical transmission link is designed to replace the waveguide transmission link, and the feasibility is verified. A flexible test network that can automatically switch to meet the requirement of parallel tests and various stages and categories of test projects is constructed. The server of test software adopts the service-oriented software architecture, and the client adopts the platform plug-in architecture to realize the ability that the test system devices can be defined, tasks can be concurrent, and processes can be customized.