In recent years, smartphone has become the most popular products, the literature for smartphone is relatively less, most of using Technology Acceptance Model ¡]TAM¡^ as the main research framework to explore. Influencing the consumer intension is concept of cognition ¡]perceived usefulness, perceived ease of use¡^, thereby affecting subsequent behavioral intentions, but what kind of product characteristics affect consumer¡¦s perceiving are seldom addressed. This study proposes "Involvement - Brand Loyalty Model" as the theoretical basis, with the "involvement" concept applied to smartphone users in order to explore the brand loyalty. Involvement antecedent focuses on "product utility", and explores what kind of product characteristics affect the product utility from the past literature, and then is combined with the social influence to investigate smartphone usage. Finally, the study will also compare different groups based on with or without owning a smartphone, and then provide the final analysis of the research results. The final results show that user involvement does affect the brand loyalty of the smartphone, and if the users are highly involved, regardless of whatever the user experience may be, product involvement will affect the brand involvement. Comparison with previous studies finds the similarity and the differences between those two groups. The common is the high involvement of smartphone. The differences lie in the user experience that does affect the user for the demand of products characteristics, and the impact of the social influence. The three products characteristics: convergence, innovation and network externality will definitely affect the product utility for someone who has smartphone, but we can understand that the user experience will impact convergence by analyzing the groups without smartphone. It is difficult to measure the value of convergence for someone who doesn¡¦t have smartphone, so in the study show that the convergence does not significantly affect the product utility, while the other two product characteristics ¡]innovation, network externalities¡^ are significant impact the product utility. For people who have usage experience, the social influence can directly affect their brand judgment, nevertheless without the usage experience, the social influence has impact on the brand involvement only through the product involvement.