Abstract: An experimental investigation has been performed and presented in the papaer to clarify the effects of low frequency vibration on the rocket moter performance which occurred a number of times during the active flight period of a missile.Firing tests of a small size motor mounted on a vibration stand simulating low frequency vibration in flight have been conducted.Some problems such as grain structural integrity,motor internal ballistic propereties and insulation erosion have been studied.The preliminary results show that low frequency vibration in flight does not destroy grain structural integrity and does not remarkably affect main motor performances,but burning rate of propellant and ablation rate of insulation in vibration direction are influenced to some extent.The research results can provid some basis for relevant engineering design.