The safety control of hydrogen is a key safety issue that must be considered in the design of nuclear power plant. In order to better study the impact of hydrogen combustion and even deflagration on the nuclear power plant, the Handan Purification Equipment Research Institute has designed and built a hydrogen deflagration environment simulation test platform, which can simulate the deflagration process of mixed gas with high hydrogen concentration range. The test results show that there are some differences in the hydrogen deflagration process of test container with different volumes. The large volume test container is more in line with the change process of hydrogen deflagration environment in serious accidents of nuclear power plant. The large volume test container has problems such as large concentration gradient of hydrogen and temperature stratification. The closer to the top of the test container, the higher the temperature. It is possible to select a suitable location to install the test equipment according to the needs. With the same gas composition conditions, increasing the initial mixture temperature can effectively improve the half peak width of the hydrogen deflagration ambient temperature curve and slow down the temperature decline rate in the simulated environment. The above experimental research lays a foundation for the equipment availability verification test in the hydrogen deflagration environment of nuclear power plant.