As the Smart phone market is growing as well as the development of society, now Thailand is full of Smart phones. In 2012, the Android and IOS system Smart phone also occupied the Smart phone market quickly. It is estimated that the Smart phone market competition will be more intense. All kinds of brands of Smart phones will choose to cut prices to attract customers, and the Smart phone market competition will be fierce. More and more customers must face the choice of which goods to buy; the competition among the enterprises is becoming fiercer. So, simply satisfying the customers achieved already can not make the enterprises survive in the industry. Therefore, the essential purpose of enterprise has become how to retain the customers and cultivate customers’ loyalty. Under this background, writers in a large number of absorbing predecessors on the basis of existing research results, by investigating the influences among the marketing mix (7P), service quality, customer satisfaction and customer loyalty, expected to explore the mechanism of customer loyalty and provide Smartphone Enterprise certain help to win the competitive advantage from the perspective of customers. This article will introduce the factors that can affect the customer loyalty from the marketing mix, service quality and customer satisfaction. Chapter 1 will introduce the whole study’s details including study questions, study benefits, scope of the study and the operating definition. Chapter 2 will review about the literature which includes conceptual framework and research hypothesis. Chapter 3 will focus on the research in research design, research tools, and the data collection and data analyze. Chapter 4 will show the result of the study. Chapter 5 will be the conclusion and discussion after the study and research. [ABSTRACT FROM AUTHOR]