Aiming at the problem of excessive noise in passenger rooms of metro vehicles in small radius curves, the influence of vehicle air conditioning system, track status and vehicle vibration on noise in passenger rooms was analyzed based on Brüel & Kjær test system. The analysis results showed that the vibration acceleration of the passenger rooms floor was 4.7 times higher than that of the straight road when the vehicle running line was small radius curve; with the increasing of the vehicle running speed, the influence of air conditioning system on the passenger rooms noise decreased gradually; and the sound source was mainly located in the middle of the door page and the floor, which was related to the rail corrugation with the significant wavelength of 25~40 mm. Passenger rooms noise was mainly affected by two factors: on the one hand, due to the low track attenuation rate, the vibration excitation input was transmitted vertically and horizontally through axle box-frame-car body, thus stimulating the structural vibration of passenger rooms to produce radiated noise; on the other hand, the rail radiated noise was transmitted to the car through the weak links of door and floor insulation after the reflection of tunnel wall was strengthened. Suggestions for operation improvement were put forward in terms of speed limit of small radius curve vehicles and periodic rail grinding.