Abstract: The nuclear power plant containment is the last barrier of the nuclear reactor, and the gas-phase leak detector is the main device for the tightness test of the penetrating parts of the nuclear power plant containment. This article describes the R&D ideas and process of the B-GLM series of gas-phase leak detectors, and has developed a set of leak detectors that can meet the tightness test of nuclear power plant containment penetrations, and can meet the personalized customization requirements of different customers. Through technical verification, it is proved that the self-developed equipment can maintain better performance and diversified expandability.