The multi-criteria vertical handoff algorithm plays an important role in heterogeneous wireless networks. There are two drawbacks in the available multi-criteria vertical handoff algorithms. The conventional algorithms do not give the feasible method to determine attribute weight values, and do not also consider the dependency relationship among the decision attributes, which are not mutually independent. These factors make it challenge to select the QoS-ensured network for vertical handoff in heterogeneous wireless networks. This paper proposes a method to determine weight values of each attribute according to the importance degree by using analytic hierarchy process. In order to eliminate the interaction among various criteria, we also propose a novel principal component extraction method based on principal component analysis, which can rapidly choose the QoS-ensured network with lower compute cost by only using less of the synthetic components. Extensive experiment illustrates the performance of the proposed algorithm compared with previous schemes, and the results show that the proposed vertical handoff decision algorithm can effectively eliminate the interaction among the original decision attributes, and extract the principal components (Only the first two principal components are able to seize 98% criteria information of the original decision information.). This algorithm can accurately select the QoS-ensured network with fewer principal components.