Provided are an unattended electric car rental system and a rental method. The system comprises a vehicle-mounted terminal, a user terminal and a management platform; and the vehicle-mounted terminal and the user terminal both perform data transmission with the management platform, and a wireless connection is formed between the vehicle-mounted terminal and the user terminal. The method comprises steps of: the management platform obtaining user information, obtaining user deposit, receiving information of a reserved vehicle, monitoring a time when a user picks up the vehicle, controlling the user to pick up the vehicle, verifying the user information, controlling starting up and running of the vehicle, controlling the user to return the vehicle, the management platform performing automatic deductions, and introducing a whole process of implementation of vehicle renting. The system provided by the invention is novel in design, and is convenient for the user to use; a rental process does not need the participation of staff members, thereby implementing unmanned renting. The method provided by the invention provides more convenience for the user in a renting process, and real-time feedback of information enables the user to timely obtain related information, thereby ensuring rights and interests of rental enterprises and users.