Voltage becomes a little lower and fluctuates seriously caused by fluctuating or impact motor loads in distribution network of power system, which influences the quality of electric energy and the operation performance of motors. A method of using series capacitors to compensate motors nearby is proposed to solve that problem. Considering the load characteristics of the motors, it concludes that regulating performance of voltage at the motor terminals is most effective when series capacitors are on the high voltage side of distribution transformer by comparing and calculating. It simulates and calculates the effects of voltage regulating performance at the motor terminals caused by series compensation device in different compensation modes. The results show that it can improve the voltage performance of motors at the ends of the line with a wide range and eliminate the voltage fluctuation caused by fluctuating loads on the condition that self-excitation is avoided when the capacitors are light over-compensated mode. It provides a new idea to improve the operation performance of motors and the quality of voltage at the motor terminals in distribution network.