Abstract: In order to solve the abnormal power picking of the electric locomotive caused by the voltage drop of the haulage network for the special heavy load coal transportation line, an analysis was conducted on the voltage transmission and lost process. The voltage lost mainly was to compensate the reactive current for the volt age lost in the system and the voltage lost in the haulage network. Thus a dynamic reaction compensation device set in the substation was provided. A proper injection of reactive power was applied to stabilize the voltage of the haulage network. Taking the Yinta substation as an example, a 55 kV wall-hooked static reactive generator consisted with 42 pairs of thyristor components was researched and developed and a control tactics with feed forward open loop and local feedback closed-loop was pr ovided to improve the response speed and steady state accuracy of the transition process. The results showed that after the dynamic reactive compensation device put in application, the average voltage value of the haulage network was increased from 46. 39 kV to 54. 40 kV and the voltage drop of the haulage network was reduced b y 52. 5%. Meanwhile, the power factor was improved from previous 0. 76 to 0.98 and the utilization rate of the power supply system was effectively improved.