The development of FCTS-S system is designed to provide a stable testing platform for fuel cell stacks. The system contains KDLF series fuel cell specific energy recycling DC electronic load, gas flow and pressure control module, gas humidity and temperature adjustment control module, cooling module, stack cell voltage detection module and sampling control and protection module, etc., it adopts the Kewell's self-developed system test software to test the output characteristics of fuel cell stacks under different working conditions. Based on online data monitoring and processing by fuel cell stack test system platform, the polarization curve, power curve and other characteristic curves of the measured cell stack can be analyzed to find the optimal output condition of the cell stack, and the output voltage of individual cells in the cell stack can be monitored. The system is applicable to the R&D and performance testing of fuel cell stacks.