Today, charging time of an electric vehicle (EV) is much longer than that for a gasoline vehicle. If an EV arrives at an overloaded charging station, it will wait for a long time. This paper investigates the waiting problem for EV charging. We propose a Mobile Charging Station (MCS) service to reduce the waiting times of EVs incurred in fixed charging station. A dispatching algorithm is presented to describe the execution flow of the MCS service. Simulation experiments are conducted to investigate the waiting time performance for the proposed algorithm. Our study indicates that by using the MCS service, the EVs can be effectively charged with short waiting times.