To explore the effects of perceived social support, stress perception, and positive coping styles on firefighters’ professional identity. A total of 362 firefighters from two teams in southwest China were investigated by perceived social support scale, the simple coping style scale, the stress perception scale, and the firefighter professional identity scale. Correlation analysis showed that firefighters’ perceived social support, stress perception, and positive coping style were significantly positively correlated with professional identity; The mediating effect analysis showed that perceived social support could affect the professional identity of firefighters through the mediating effect of stress perception and positive coping style, and it could also affect the professional identity of firefighters through the chain mediating effect of stress perception and positive coping style. Stress perception and positive coping style play a chain mediating role between firefighters’ comprehension, social support and professional identity.