Abstract: OBJECTIVE To explore the process of preparing the drug number and duration of interruptions and the resulting disruption factors, which provide guidance for the nursing staff due to drug preparation process interruption caused by medical errors. METHODS Continuous observation of the daily work of nursing staff during the period June 2015 to December 2015, recording the process of preparing the drug number and duration of interruptions occurred during all the nurses, and to analyze factors leading to its interruption, the results were statistically treatment. RESULTS The study collected a total of 832 pharmaceutical preparation, which interrupted 751 cases, the average number of interruptions was (6.1±0.7), with the average duration was (6.5±2.4)min, leading to disruption of factors including physician summoned patient calls, receive calls, answering and colleagues about their families and other human factors and material handling, information entry and release of drug and other non-human factors. CONCLUSION The nursing staff during the course of preparation of the drug, the number of frequent interruption, long duration, multi-factors. Therefore, care workers should pay attention to analysis of drug preparation process interrupt factors, to reduce unnecessary interruptions, thus reducing the preparation process due to drug interruption caused by the incidence of medical errors.