With the rapid expansion of the road networks and growing number of vehicle ownerships in many countries and regions, the severe green-house-gas and pollutant emissions from internal-contusion-engine (ICE) based vehicles have been the cause of much concerns about their impacts on human health and climate change. To address these problems, the replacement of traditional fossil fuel vehicles with electric vehicles (EVs) has become a global trend. In order to power the EVs, in particularly heavy-duty trucks, the electric road system (ERS) has been proposed and piloted in several countries and regions in recent years. It can supply power to EVs while driving, hence relieve the pressures on EV drivers to travel to a fixed location for charging as well as long waiting for charging time. This paper presents a brief review of the ERS, covering the concepts, power supply types, advantages and disadvantages of different power supply modes, risk assessment and maintenance. Finally, the current technical challenges and future development prospects are discussed.