The fatigue failures frequently occur to the metro vehicle's bogie frame during the service life， and some of them are located near the motor mounting base. That indicates some special loads such as motor vibration are ignored or misunderstood in the traditional anti-fatigue design， which leads to the insufficient fatigue life of the frame. To study the effect of motor traction vibration on the frame's fatigue life， a metro vehicle bogie frame is taken as a case study. First， the frame's finite element model is established， and its accuracy is verified by experimental modal analysis. Second， through the frequency sweep calculation， the dynamic stress response characteristics of the frame under the motor vibration excitation are analyzed， and the transfer relationship between the motor vibration acceleration input and the dynamic stress response output is obtained. Finally， Taking the measured motor vibration acceleration signal of a metro line as the input condition， the effect of random vibration on the fatigue life of the frame under traction and idle running conditions is compared and analyzed by solving the power spectral density of dynamic stress response at the weak fatigue point of the frame. The results show that： under the excitation of the motor， the vibration energy mainly concentrates on the modes 6，7 and is excited by the transverse and vertical vibration of the motor， respectively， which contributes significantly to the fatigue damage of the frame. Compared with the idle running condition， the fatigue life of the frame's key position under traction condition is greatly reduced. It is proposed that the effect of motor traction vibration on fatigue life should be fully considered in the Metro frame design.