Users can have access to resources and obtain services at anytime and anywhere in ubiquitous computing environment. By virtue of behavior experience in human society, according to dynamic evolution discipline of the contradiction between the lag of trust and the anteriority of service, and the self-organization, distributed computing and regenerative feedback characteristics of ant colony algorithm, cascade service selection model based on ant colony algorithm is put forward. It examines ubiquitous equipment' trust degree before ants choose the next hop, the best server satisfied with the ubiquitous entities' request was selected out by means of cascade servers to improve the service of quality and efficiency, which conquers the disadvantage that a singular equipment can't satisfy the request property and blindfold choice of service. Experimental results show ubiquitous entities can correctly select optimum network services in short time via this model.