The problem of Temporal Constraints based QoS-aware web Service Composition (TC_QSC) is becoming increasingly critical in recent years.Its objective is to select the Web service composition which maximizes the QoS utility while preserving QoS constraints and temporal constraints.This paper proposes a temporal constraints decomposition method that formulates the TC_QSC problem into a general QoS-aware Web service composition (QSC) problem by means of decomposing the temporal constraints imposed on the whole or part of the workflow to a set of local temporal constraints for each activity.So the problem scale is reduced by filtering out those candidate web services violating local temporal constraints.The temporal constraints decomposition process is mainly dependent on the workflow and activities involved in it

while it has little to do with the candidate services.Therefore

its complexity is lower.The experiments have demonstrated the effectiveness and time cost of the proposed method and verify its necessity to local selection algorithm.