Abstract: Advanced a method of Web service selection based on SPA. The method includes two parts: one is determining sameness, difference and opposition measure intervals of QoS criteria by non-functional constraint of Wcb service; the other is evaluating candidate simple and convenient method of service by connection-degree and set pair shi With instance testification, it is a very Web service selection on condition that ensures the accuracy.

Key words: Service selection, Measure interval, Connection-degree, Set-pair shi