Abstract: When helium mass spectrometry is used to detect the leakage rate of double sealed structure products,the stability time of leakage rate is long,and the detection efficiency is low.To solve this problem,a leakage model of double sealed structure is established,and the leakage curve is analyzed.On this basis,a stable leakage rate determination method based on exponential function fitting is proposed,and three leakage curves of different magnitudes from 10^-6to 10^-8Pa·m³/s are fitted and analyzed.The results show that the method can effectively solve the problem of stable leakage rate determination and improve the efficiency of leakage detection.