A parking lot reservation system in which each vehicle sends to a remote server through a GPRS module a park reservation request carrying the information of the ID code and current location of the vehicle and specific conditions, and the remote server searches a parking lot database to select the qualified parking lot information subject to the park reservation request and then sends a reservation command to the parking lot computer of the associated parking lot through the Internet to finish the reservation. After success of reservation, the parking lot computer sends a response message indicative of successful reservation to the GPRS module of the vehicle via the remote server.