Presenteeism behavior has gradually attracted the attention of management practitioners and has become an important issue for management scholars and psychologists. Based on the job demands-resources theory model and the conservation of resource theory, this study explores the impact of job demand on presenteeism behavior in the Chinese context through a questionnaire survey, and put forward a moderated mediation model. The research results show that: job demand is significantly positively related to job insecurity and presenteeism behavior; job insecurity plays a mediating role between job demand and presenteeism behavior; at the same time, psychological capital can buffer the negative impact of job demand on job insecurity, thereby avoiding the occurrence of presenteeism behavior. This study expands the scope of psychological capital research and provides a new perspective for studying presenteeism behavior. These research conclusions provide important theoretical support for companies to eliminate or limit employees" presenteeism behavior as far as possible.