A new control method is proposed to enhance the stability of railway vehicles with additional mass without modification of the bogies. Two mass are set on the bogie and controlled by actuators. Each of the mass has a lateral degree of freedom relative to the bogie. The motion of two mass used to suppress the lateral and yaw vibration of the bogie respectively. The control algorithm is designed based on full-state feedback control theory and optimal control theory. A dynamic model is established and analyzed on MATLAB/Simulink. The control method is analyzed in both time-domain and frequency-domain. The results show that the critical speed of the bogie is enhanced. The dynamic performances of the vehicle are also improved in all speed range.