Based on data from car dealers in China,this study examines the impacts of perceived organizational support (POS) and guanxi on personal performance and the mediating role of customer need knowledge (CNK).Results indicate that salespersons' POS and guanxi with customers have a positively influence on their CNK and job performance; their CNK is also positively related to job performance.Meanwhile,CNK acts as a full mediator between salespersons' POS and their job performance,and as a partial mediator between salespersons' guanxi with clients and their job performance.