Motivated by the problem of simplifying the manual operation of the composition process, we propose an approach to automatically compose available Web services to fulfill user’s goal based on the assumption that there are a set of alternative Web services with similar functionality and different QoS proper-ties. A formal model (i.e. semantic links matrix, SLM for short ) is proposed to store semantic links values for the Web services with semantic relationship and QoS of Web services. The SLM pro-vides a search place for a backward-search planning algorithm, at the same time; the QoS criteria make a rational and effective deci-sion among a number of similar Web services. The function and some properties of the algorithm are analyzed. The approach can improve the correctness and flexibility for Web services composi-tion and satisfy the local QoS attribute. Motivated by the problem of simplifying the manual operation of the composition process, we propose an approach to automatically compose available Web services to fulfill user’s goal based on the assumption that there are a set of alternative Web services with similar functionality and different QoS proper-ties A formal model (ie semantic links matrix, SLM for short) is proposed to store semantic links values ​​for the Web services with semantic relations and QoS of Web services. The SLM pro-vides a search place for a backward-search planning algorithm, at the same time; the QoS criteria make a rational and effective deci-sion among a number of similar web services. The function and some properties of the algorithm are analyzed. The approach can improve the correctness and flexibility for Web services composi-tion and satisfy the local QoS attribute.