The work aims to analyze the influence of vent area and opening pressure threshold of the slave-master airbag on the airbag impact acceleration, speed and other cushioning characteristics, so as to improve the airbag cushioning performance. The theoretical model for the slave-master airbag with the opening vent thresholds was established according to the relevant theories of dynamics and thermodynamics. The increase in the master airbag’s vent area could reduce the first peak of the load acceleration and increase the second peak. Reverse effects would be achieved with the increase in the master airbag’s exhaust threshold. The increase in the vent area of the slave airbag, the second acceleration peak of the load would be reduced. Reverse effects would be achieved with the increase in the slave airbag’s exhaust threshold. Through the analytical model herein, the vent area of the slave-master airbag was reasonably designed. The opening threshold set for the master airbag vent can effectively reduce the airbag overload and it has improved the strong cushioning performance.