Smart phones become essential goods for our life. As the technology are developing, and the market becomes saturated, it is important to understand the determinants affecting purchase of smart phones. In this paper, to understand these determinants factor analysis and binary logistics regression is used. Toward this, we first define the determinants into 3 categories: customer satisfaction, switching barrier, and switching attractiveness based on literature review. Furthermore, we develop 9 hypotheses to test with survey data using factor analysis and binary logistics regression. The results show that the six factors (data quality, price satisfaction, corporate image, the burden of new contract, attraction of devices and attraction of other competitors) are significant when customers buy smart phones.