With the advent of smartphone, customers purchasing smartphones are sharply increasing over years. Since the Smartphone market extend, the major brands are getting more competitive. Each brand manufacturers are dedicating in developing a strong operating system, software applications, fashionable appearance, service quality, and so on. The purpose of this study is to explore consumers’ purchasing behavior, determinants of purchasing decision, and factors of brand loyalty of smartphones. The findings stated that some external factors markedly influenced customers on choosing smartphones. For example, a customer bought a smartphone because of the demand for using it. On the contrary, few customers would buy a smartphone due to the pursuit of vogue or modern trend and the influences by other people. Furthermore, some internal elements of decision processes have sharply influence on choosing a smartphone. The majority of respondents agreed that the price, internal functions of a smartphone all played an important role on making a purchasing decision. In the opposite side of our original thinking, ninety-three respondents (37%) disagreed that they would choose the one with lower price between two smartphones. In the third part related to the brand relationship quality for purchasing a smartphone, most respondents could hurriedly recall the symbolic logo of the brand and the after-sale service would affect their willingness of rebuying the same brand. In contrast, even though the evaluation of this brand is not good, they still intend to continue to buy this brand. Finally, brand loyalty led consumers to happily tell others the advantages of this brand and recommend the purchase, and to rebuy the brand when it launches a new product. In conclusion, Customers’ perceived value, brand experience, trust, satisfaction, service quality and commitment are found to be the key influencing factors of brand loyalty.