Modular bridge expansion joints（MBEJs）is a common form of bridge expansion. So far，it is widely used by different kinds of bridges. However，the noise of joints under vehicle load is still a problem，which seriously influence the life quality of surrounding residents. The paper takes MBEJs as the research object to study the vibration characteristics and noise characteristics of the expansion joints. Several finite element analyses（FEA） are conducted to study the influencing factors of the first-order vertical mode and the variation laws of multiple modes of MBEJs. Besides， analyses for the acoustic frequency responses of joint-cavity system and the acoustic modal responses of the cavity are conducted by using the numerical simulation method. The above results are compared to study the generation and transmission mechanisms for noise of joints under vehicle load. The results show that noise of MBEJs is caused by coupling action of vehicle-induced vibration excitation and cavity acoustic mode excitation. The noise can be reduced by packing and sealing the lower cavity of expansion joint.