This paper aims at the reduction of noise derived from the vibration of relay. Firstly, the noise source of the battery pack is found out through the vibroacoustic test, combining the frequency response function with the vibration spectrum characteristics. Secondly, based on the improvement of transfer path of the vibration of relay, a kind of rubber isolation pad with low stiffness is designed to filter the medium and low frequency vibration of relay so as to realize the noise reduction of the battery pack. Finally, the results indicate that the vibration of relay is passed directly to the shell of battery pack by the rigid connected bolt, which results in the vibration of shell and radiated noise. The rubber isolation pad designed in this paper can effectively filter the medium and low frequency vibration of relay to realize the noise reduction. When the upper cover plate is open, the total sound pressure level is reduced by about 6 dB; when the upper cover plate is closed, the total sound pressure level drops nearly 11dB.