###### Abstract
There are now studies pointing out that, being something new in the developmental stage of mobile media, privacy fatigue may be an important cause affecting the privacy paradox [9]. Thus, the issue of privacy fatigue is not only a new topic in privacy security earnestly awaiting research, but also a strong perspective to explain the user privacy paradox in the new stage of social media. Though the significance of privacy fatigue has already been noticed, at present, its roles in the privacy paradox and how much it can explain the paradox have still not been clearly delineated in research. To better understand how privacy fatigue acts in user privacy behavior decisions on mobile social media, more studies are needed. Furthermore, since personal privacy is a constituent of \"individual personality rights\" [12; 13], personal characteristics can explain and predict sensitivity towards privacy concerns and privacy fatigue in users [14]. However, previous studies on privacy found it very hard to discern confounding factors' effects on privacy decisions. Their findings are often very vague [15]. At this juncture, prior studies on privacy fatigue are very limited, with even fewer researching personal characteristics as influencing variables. Considering this status quo, an exploration of the effects from user heterogeneity is added in this paper, which would be helpful in supplying a theoretical reference to the adoption of differentiated protection practices for users. Summing up the above, the research questions raised by this research are:  
1. Is privacy fatigue among users of mobile social media the reason leading to the phenomenon of the privacy paradox? 2. Would individual differences among users of mobile social media affect the explanatory strength of privacy fatigue in the privacy paradox phenomenon? In order to answer the research questions above, this study introduced the Elaboration Likelihood Model (ELM) to construct the research model suitable to the research context. The influence from privacy fatigue on the privacy paradox is considered the central route, with heterogeneous influences of users' individual differences being the peripheral route. In addition, in order to control and eliminate selection bias caused by confounding variables, the paper employed Propensity Score Matching (PSM) as the data analysis method to simulate a scenario of individuals with the same level in their characteristics undergoing experimental intervention, so as to lower confounding bias. This study intends to commence from the angle of privacy fatigue to explore its action mechanism in the process of the privacy paradox, aiming to provide important theoretical references for comprehending privacy behaviors of social media users and be of help in resolving the user privacy issue in the new stage of social media digitization. The rest of this paper is organized as follows. Section 2 is the literature review, which briefly discusses prior studies concerning the privacy paradox and privacy fatigue. In Section 3, we introduce the paper's theoretical backgrounds and propose the study's research framework and hypotheses based on the theoretical buttresses. The research design as well as the process of data analysis and results are shown in Sections 4 and 5. Finally, Section 6 is the summary of the paper.