In order to provide high Quality of Service (QoS), rational scheduling and resource allocation are needed when a great deal of tasks requesting grid resources. By quantifying some important properties of Grid QoS and maximizing cost-performance ratio of Grid system, a QoS-guaranteed self-adaptive grid resource selection algorithm based on SAGA which is named QoS-SGRSA is proposed, and the flow of the algorithm is introduced. In the low load condition, traditional resource selection algorithm is adopted, so an allocation policy is found rapidly. While in the high load condition, by means of using complementary advantages of GA and SA, it can guarantee that the search is on the optimization direction. Finally, we evaluated the effectiveness of QoS-SGRSA by emulation experiments.