Resource sharing method and device are provided. The method includes: sending an access request to a second communication network through a target backhaul link of the second communication network by a resource sharing device when the access request is received from a terminal from a first communication network; sending the access request to the first communication network by the second communication network, for authenticating the terminal; sending QoS level information of the terminal to the second communication network by the first communication network when the terminal is authenticated, and sending access rejected information to the second communication network when the terminal is unauthenticated; providing services for the terminal according to the subscription QoS level information, or rejecting to provide services for the terminal according to the access rejected information. The present disclosure realizes sharing of backhaul resources of different communication networks and ensures the QoS of the resource sharing device.