Mine electric locomotive is an important transport machine of the mine ground and underground tunnel, its working conditions are complex and has a poor operating environment. In order to improve the traction motor speed control performance and improve the system anti-disturbance and the robustness to the parameter variation, the speed controller of the control system is proposed, which uses fractional sliding mode to replace the traditional PI control. Aiming at load changes in the running process of the electric locomotive, the load torque observer is designed to observe the load torque in real-time, the observed value is integrated into the control strategy, which can improve the speed of the load mutation control. Simulation results show that the load observer can observe the load torque quickly and accurately. The sliding mode speed control with load observer has a strong anti-jamming effect on the load disturbance and effectively restrains the inherent chattering of the sliding mode control.