The HETS-PWE-S-500 system is aimed at providing the PEM electrolyzer with an accurate and reliable test platform for PEM electrolyzer. The system consists of deionized water circulation system, pressure regulating unit, gas-water separation unit, gas dry and flow monitoring unit, sampling and control unit and safety monitoring unit. The system test software independently developed by the company is used and it can meet PEM electrolyzer performance, durability, reliability and safty test. The system is applicable to the R&D and performance testing of 500W PEM electrolyzer.