Abstract: In order to solve the problem that the fracturing isolation system has low pressure and cannot return to the wellbore in time in the completion of casing branch wells in offshore oilfields, which affects the efficiency of completion operation, we designed a new type of temporary plugging tool. The process principle and structural composition of the tool are introduced in this paper. The size parameters of the temporary plugging tool are determined by the mechanical analysis of the rupture disc. The static finite element analysis of the bearing capacity and crushing load of the rupture disc is carried out, and the performance test is carried out. The function relationship between the thickness of the rupture disc and the variables such as the rupture pressure and the temperature coefficient is fitted. Theoretical analysis and experimental results show that the designed temporary plugging tool can bear the pressure of 35 MPa, and with a 12 t impact load, the rupture disc of the temporary blocking tool can be broken into less than 5 mm × 5 mm × 5 mm fine particles which can be easily discharged out of the wellbore. This temporary plugging tool can meet the technical requirements of casing branch well completion in offshore oilfields, and it has certain popularization and application value.