A micro pressure automatic inflation system was designed to address the issue of missed detection under atmospheric pressure for three-stage diaphragm tanks.The system achieved automatic inflation and overpressure control in the gas and liquid chambers under micro pressure conditions，and solved the problem of missed detection helium gas leak detection under atmospheric pressure.Comparing and analyzing the micro pressure automatic inflation system with traditional manual inflation operation，the results show that the flow design of the micro-pressure automatic inflation system can reduce the high-pressure helium gas to micro-pressure levels of 10 kPa，120 kPa，the overpressure reversal of the diaphragm can be effectively avoided through the setting of the system''s back pressure valve，the missed detection effect is significantly better than that of normal pressure helium mass spectrometer missed detection.This research ensures the safety of the helium leak testing process for diaphragms within the tanks，enhances the reliability of the quality of three-level diaphragm tanks，and can be applied to subsequent micro-pressure inflation tests for other products.