Abstract: Objective: To explore the relationship between clinical nurses' knowledge sharing behavior on their core competency. Methods: A total of 448 nurses from three tertiary hospitals in Hunan were recruited and investigated by the Knowledge Sharing Behavior Scale and the Competency Inventory for Registered Nurse (CIRN). And the relationship between knowledge sharing behavior and competency inventory was analyzed. Results: The mean score of the Knowledge Sharing Behavior Scale and the Competency Inventory for Registered Nurse were (2.36±0.69) and (2.78±0.55),respectively. The total score and the score for each dimension of the Knowledge Sharing Behavior Scale were all positively correlated with the total score of the Competency Inventory for Registered Nurse (P<0.01). Stepwise multiple regression analysis have shown that the score for three dimensions of the Knowledge Sharing Behavior Scale such as organizational communications, personal interactions and communities of practice could explain 39.9% of the variance for clinical nurses' competency inventory after controlling the demographic variables. Conclusion: Nursing administrators should take scientific and feasible intervention measures to improve clinical nurses' knowledge sharing behavior and promote the development of nurses' core competency based on the present situation of clinical nurses' knowledge sharing behavior.