基于压差法的薄膜透气性测试装置，在压力和温度检测器的检测性能给定和环境温度相对稳定的情况下，影响测试结果的主要因素是测试装置的密封性能。为了同时提高测试装置的密封性能和测试精度,提出了3层密封结构设计的模型，建立了相应的数学模型,并给出了因泄漏而引起压强变化的特性和仿真结果。为3层密封结构薄膜透气性测试装置的实际应用提供了理论依据。

For film gas permeability test device based on differential pressure, when the performance of pressure and temperature detector is given and the test temperature is relatively stable, the test result is decided by seal performance of test device. To improve the seal performance and test performance of test device, the model of three layers sealed structure was presented and the corresponding mathematic model was established. The feature of pressure change caused by leakage and its simulation result were given. The purpose was to provide theoretical basis for practical applications of film gas permeability test device with three layers sealed structure.