Ubiquitous computing intends to embed the entire computer system into people's daily life. It does not en-force users to have sophisticated knowledge about computers. Instead, the ubiquitous computing system provides ahighly adaptive application environment by coordination of individual computing equipment. After a discussion on basicconcepts of ubiquitous computing as well as basic man-machine interactions ,this paper proposes some basic ubiquitouscomputing models including the user-centric computing model and the service-centric computing model. Extensive dis-cussion on advantages and disadvantages of these models are also given.