The invention provides a directory-based access network fusion method for heterogeneous wireless environment, wherein the hardware platform comprises a terminal unit (1), a signaling base station (2), N service base stations (3), a core network, Un signaling channels between the terminal unit (1) and the signaling base station (2), Uu service channels between the terminal unit (1) and each service base station (3), Iu signaling channels between the signaling base station (2) and the core network, and Iu service channels between each service base station (3) and the core network. The method comprises the following key steps: directory indexing step, terminal start-up step, service establishment step, directory update step, and mode switching step. The invention incorporates the common access of control signaling, various modes of service communication and directory-based access management strategy, facilitates the selection and switch of communication modes, improves the management logic, coverage flexibility, switch flexibility and access controllability, and provides the extensive support. The invention is a high-efficiency proposal to access network of heterogeneous wireless network.