Abstract: A physical and mathematical model for the differential pressure leak detection is established in the paper. The pressure and temperature responses are calculated and analyzed based on Matlab numerical simulation software for different parameters, such as charging time, heat transfer coefficient, effective heat transfer area and irradiation coefficient. The results show that the longer the balance time, the smaller the differential pressure and temperature. When the master volume is smaller than the tested volume, the differential pressure and temperature can be reduced by increasing the tested tank parameters, such as effective heat transfer area, heat transfer coefficient and irradiation coefficient.