As organizational environments become increasingly turbulent and complex, there is need to focus on creating high-quality employment relationship for many organizations. For years, the distinction between ‘insider’ and ‘outsider’ employees has been formally utilized throughout both the academic and practitioner literature. Perceived insider status refers to the extent to which an employee perceives him or her as an insider within a particular organization. It is a key indicator of the relationship between employees and the organization that influence their perceptions of inclusion, so many organizations can gain labor efficiency and competitive advantages. Nowadays studies have demonstrated that perceived insider status has a positive effect on organizations. Few studies, however, have explored factors of perceived insider status. The aim of this study is to investigate ‘how’ increasing social resources influences new employees’ insider status perception. Drawing on the within-person level, therefore, this study examined the effect of increasing social resources on new employees’ insider status perception and tested the multiple mediating roles of person-organization fit in this process (person-job fit, person-group fit and organization value fit). To test our proposed model, we surveyed 69 new employees in Chinese enterprises using experienced sample methods and diary study. We got 69 questionnaires and 523 pieces of within-person data. Established measures with high reliability and validity were used to capture key variables. Multilevel linear model analysis was mainly conducted for data analysis. Consistent with hypotheses, it was found that: (1) All variables, increasing social resources, person-job fit, person-group fit, value fit and perceived insider status, had short-term fluctuations. Within the sampling period, the percentage of individual variation of these variables ranged from 54.76% to 68.75%. (2)Weekly increasing social resources promoted weekly person-job fit (γ= .32, p< .000), thereby enhancing weekly perceived insider status (γ=.17, p< .01). The mediating effect of weekly person-job fit was significant (ind =.054); (3)Weekly increasing social resources promoted weekly person-group fit (γ =.35, p<.000), and then enhanced weekly perceived insider status (γ =.12, p <.01). And the mediating effect of weekly person-group fit was significant (ind =.044). (4)Weekly increasing social resources promoted weekly value fit (γ =.48, p <.000), and then improved weekly perceived insider status (γ =.15, p <.05). The mediating effect of value fit was significant (ind =.072). However, there were no significant differences among these mediating effects. Our findings contributed to current literature in three ways. First, drawn from the perspective of the individual, this study explored the dynamic change mechanism of the new employees’ insider status perception, which enriches the theoretical research results of insider status perception. (2) Focus on the new employees' behavior of increasing social resources, this study analyzed its positive role in insider status perception, and expanded the scope of research on job crafting. (3) This study incorporated the three levels of person-job fit, person-group fit and value fit into the content system of person-organization fit at the same time, and tested the multiple mediating roles of person-organization fit in the formation process of new employees' insider status perception completely, which can promote the development of the theory of person-organization fit.