A method for calculating the tearing force of a new type of tearing device for aerostat was studied based on the theory of linear elastic fracture mechanics. Firstly,the critical strain energy release rates GICand GIIICof the film materials were obtained by fracture tests of type I and III. The FEA Models of the tears-I,tears-III and the tearing device were constructed by Debond and VCCT technology. The Power model was selected as the crack extension criterion,and the index in the Power model was fitted by the FEA results and test results of Type I and Type III tearing respectively. Finally,the tearing force of the tearing device was calculated based on the finite element model and the power model. The effectiveness of the results was verified by physical experiments,indicating that the calculation method of the tearing force for the new tearing device is feasible.