Demand responsive transportation system (DRTS) is very suitable for solving the public transportation problem in remote areas, and alleviating the operation load of the conventional bus operators at the same time. Aiming at the scenario of introducing a real-time booking service of DRTS into Fuxing District of Taoyuan City, this research uses system simulation to conduct the service performance evaluation. The results show that the performance increases with the expansion of fleet size by service waiting time, travel time, service time, and number of failures at first booking. Nevertheless, the performance increases with the reduction of fleet size by operating mileage, vehicle idle time, and average number of occupied passengers. Regarding the service time as the service cost of DRTS for passengers, and the vehicle idle time as the opportunity cost of the DRTS operator, the total cost, about 560 hours, is minimum by a fleet size of 22 vehicles under the assumption of equal value for both costs.