Abstract: Research on the buffering protection of missile borne instruments under impact loads has received much attention. Aiming at the problem that the pulse width of high overload signal affects the cushioning efficiency of the cushioning material foam aluminum in live ammunition test, a research method of cushioning efficiency based on air gun test was proposed. The buffer model of the buffer test device was simplified to a single degree of freedom buffer model, and the stress-strain curve of foam aluminum under the high overload signal buffer compression was analyzed and established. It is found that the pulse width of the high overload signal affects the stress and buffer efficiency of the plastic platform area by affecting the strain rate of the high-density foam aluminum, while the buffer efficiency of low-density foam aluminum is basically not affected by the change of pulse width. The research results show that when the amplitude of high overload signal is about 20 000g, the pulse width decreases by 111 μs, the stress in 1. 55 g/cm~3 foam aluminum plastic platform area increases by about 15 MPa, and the buffer efficiency decreases by about 5. 97%; The amplitude of 0. 5 g/cm~3 foam aluminum at high overload signal is the same, the pulse width decreases by 126 μs, and the stress and buffer efficiency in plastic platform area remain basically unchanged.