Objective To investigate the current situation of knowledge, attitude and practice（KAP） of excessive oxygen therapy among medical staff in the emergency department, and explore its influencing factors, in order to provide a reference for clinical oxygen therapy training and standardizing oxygen therapy practice. Methods A total of 998 emergency department medical staff in 20 secondary general hospitals and above in 10 provinces across the country were surveyed using the KAP questionnaire of medical staff on excessive oxygen therapy. Results The total score of the KAP questionnaire of medical staff on excessive oxygen therapy in the emergency department was (120.76±13.61), and the scores of knowledge, attitude and practice dimensions were (29.54±5.45), (41.60±4.44) and (49.62±9.49), respectively.The results of multiple linear regression analysis showed that the main influencing factors of knowledge, attitude and practice of excessive oxygen therapy in emergency department medical staff were hospital level, whether they had studied relevant literature in the past 12 months, occupation, whether they had participated in relevant training, position, etc. (all P＜0.05). Conclusion The KAP of excessive oxygen therapy of medical staff in emergency department are at a medium level.It is suggested that hospital managers should train emergency department medical staff on the knowledge of excessive oxygen therapy according to its influencing factors and change medical staff′s oxygen therapy concepts, so as to standardize clinical oxygen use and improve the quality of oxygen therapy.