Abstract: In heterogeneous networks vertical handoff is carried out more complexly than horizontal handoff in homogeneous networks.It is a multi-objective decision making which is dominated with different network parameters.In this paper, the handoff mechanism is proposed.By the network interface activating interval adaptively, the terminals which have the function of power saving can find usable networks which are in good link-state.Then, the target network is selected using the decision function to meet user and application QoS requirements.In order to eliminate network and parameter differences, the different parameters are standardized in the decision making.