Internetware is an abstract of software system in open network environment. Its trust relationship is one of the most complex social relationships. In order to enhance adaptability of trust evolution model, improve prediction accuracy about trust evolution, and restrain production of selfish nodes effectively through discriminatory service and evolutionary game theories, this paper puts forward a trust evolution model that corresponds with characters of an open network: (1) Global profit function of entities based on discriminatory service is gained for enhancing adaptability of trust evolution model; (2) With the help of evolutionary game theory, and based on characters of Wright-Fisher model, a kind of Wright-Fisher multi-strategy trust evolution model of internetware is proposed for enhancing the prediction accuracy about trust evolution; (3) According to principle of fairness, incentive mechanism based on game is built, so as to inspire evolution of trust strategy and restrain production of selfish nodes effectively. The experimental results show that this model can more accurately reflect complexity character of open network. By adding incentive mechanism, internetware system can achieve the stable state more quickly, thus it can improve the efficiency of network more effectively and make the trust profit achieve optimal.