Based on trust behavior experience in human society and the law of gravity，this paper introduces a concept of trust gravitation to analyze the trust relationship between pervasive interaction entities. Then built a sound svstem is built in terms of a service evaluation and selection model based on trust gravitation. The system that integrated direct，indirect and historic evaluation is tested to improve the efficiency and veracity of service evaluation and selection．Experimental results show that pervasive entities can select optimum netWork services in short time via of this model．