A method for providing public and private mobile communication service in a mobile communication system. The system constructs a mobile communication network including a private base station transceiver subsystem (Base station Transceiver Subsystem) of a private mobile communication network and a plurality of base station transceiver subsystems of a public mobile communication network, which includes mobile switching centers (MSCs), base station controllers (BSCs) connected to said each mobile switching center, and the base station transceiver subsystems connected to said each base station controller. Upon receipt of a service request from a mobile terminal through at least one of the base station transceiver subsystems including the private base station transceiver subsystem, the system determines whether the requested service is a public mobile communication service or a private mobile communication service; and accesses a network corresponding to the determined one of the public and private mobile communication services, and providing a corresponding mobile communication service to the accessed network.