Benefiting from the popularity of Social Network Site (SNS), the Social Network Site based Entertainment Applications (SNSEAs) have been reaching a wide range of users. However, research on design factors in the SNSEAs and the outcomes of incorporating these factors into SNSEAs is still scant, especially for the phenomenon of user stickiness in this context. Studies on SNSEAs are believed to have a significant contribution to both the Social Network Site researchers and practitioners. This study is developed to investigate the design factors of SNSEAs and antecedent of user’s stickiness through an empirical study. Based on flow theory, perceived playfulness of SNSEAs is identified as the direct antecedent, which is found to be affected by four design factors (i.e., Symbolic Physicality, Inherent Sociability, Multiplay Asynchronicity, and Inter-application Interactivity).