Structural dynamic performance analysis based on frequency response and modal contribution amount was presented about the problem of vibration and noise of helicopter main gearbox housing. The mode contributing most to the structural frequency response was found based on structural vibration performance. A method of analyzing panel acoustic power contribution amount of helicopter gearbox housing was presented based on combination of finite element method and indirect boundary element method. Acoustic radiation of the housing was simulated. The panel contributing most to the structural acoustic power under corresponding frequency was found. The panel mentioned above was the optimization area; stiffeners were reasonably arranged on the panel according to the optimization output. Result shows that

the maximum velocity frequency response has decreased 36%

vibration of the housing is attenuated

peak value of acoustic power level has decreased 5dB

and noise of the housing is reduced

which provides a feasible method to reduce noise and vibration for helicopter main gearbox housing.