OBJECTIVE： To provide reference for avoiding the recurrence of medical safety （adverse） events or inducing more severe medical accident. METHODS： The medical safety （adverse） events reported by a class A grade 3 hospital from July 2013 to March 2016 were studied retrospectively， and excluded purely adverse drug reactions and transfusion reactions to analyze the reason and characteristics. RESULTS： Of 747 events， there were 578 medical， nursing and drug-related medical safety （adverse） events， accounting for 77.38％； among 175 medical related medical safety （adverse） events， top 3 reasons were basic skills deficiencies， defects in the system processes， inadequate communication and education，  accounting for 32.00％， 24.00％， 19.43％. The occurrence of medical safety （adverse） events were closely related to working life and qualifications； among 578 medical， nursing and drug-related medical safety （adverse） events， the incidence of adverse events was 71.11％ in 5-year working life group， and that was 73.18％ in junior titles group. CONCLUSIONS： Various professionals should strictly implement procedure and regulations， strengthen communication and education in daily work， and improve professional knowledge and skills so as to prevent the occurrence of adverse event completely.