Recent technological advancement in Telecommunications industry has enabled service providers and application developers to offer some of their services which used to be solely PC based for mobile devices as well. Given the prevalence of mobile data services, specifically mobile social network services, and application-stores such as Market (Andriod) and AppStore (Apple), it is crucial to understand user behaviour toward mobile service diffusion. The present study aims to investigate Chinese users’ behaviour toward mobile social network services, based on a sample of 212 respondents who used the most popular mobile social network services such as Tencent QQ in China. Our analysis suggests that each construct, perceived enjoyment, social influence, critical mass and mobile accessibility of social network service makes a unique contribution to our understanding of mobile social network service usage behaviour.