In this paper，the characteristics of the vibration environment for helicopter airborne equipment are described briefly. The energy equivalence principle is proposed for the conversion of the sine-random hybrid vibration to the broadband-narrowband random vibration. Then，the setting mode of boundary conditions and the specific simulation steps are discussed in detail. This method makes the computer simulation be available for usage. Modal simulation and random vibration simulation are successfully conducted to the structure of power box shell. Vibration response results and the maximum equivalent stress of the shell under excitation spectrum are obtained. The reason for energy mutation and the judgment method for stress results are analyzed as well. Finally，the reliability of simulation results is verified by experiments. Research results can sever to provide a theoretical basis and realization method for the vibration simulation of helicopter airborne equipment.