With the growing use of social media in the world, a wide variety of social media applications and services have been produced. Popular social media platforms leverage their unique functions to persuade their users to adopt such applications and services, and many enterprises have begun to consider social media operations as a crucial aspect. Thus, since the gradual influence of social media on consumer behavior, a new social commerce model has begun to develop. This research examined both business and social aspects of social commerce sites to establish an evaluation model for measuring their quality and effectiveness. We collected 468 valid samples of online users who had used social commerce site to browse or purchase products and were willing to use again. We used EFA and CFA to confirm the model we constructed, and Partial least squares regression was used to analyze the relationship among the antecedents and consequences of quality evaluation in social commerce sites. According to the result, the consumers’ behaviors were most likely affected by functionality, enjoyment, process, reliability, presence, and identity with a social commerce site. This study not only provided a credible social commerce quality measurement for other scholars to conduct relevant research but also provide conclusions for the marketing strategy of social commerce sites and products as a reference.