Objective By summarizing the causes of adverse reaction of nonprescription Chinese medicine，we provide a reference for the safe use of Nonprescription Chinese medicine. Methods Set the scope of Chinese medicine：Traditional Chinese medicine，Traditional Chinese and Western Medicine，The preparation of Chinese medicine extract. Use the research methods in regression，by retrieving it in National Center for ADR Monitoring of State Food and Drug Administration，Adverse Drug Reactions Journal and Chinese Journal Full Database，summarizing the nonprescription Chinese medicine which have adverse reaction and analyzing the causes of adverse reaction. Results There are many factors influencing the adverse reaction of nonprescription Chinese medicine， such as drug factors，combination therapy，the distinctive between drugs and syndromes， physical factors，inappropriate medication，including toxic Chinese medicine，immature of Chinese medicine westernized. Conclusion The adverse reaction of nonprescription Chinese medicine related to many factors. In clinical application，we advise that giving full consideration to all aspects of it， increasing the monitoring and report of adverse reaction and consummating the research of adverse reaction mechanism，provide a reference for the safe use of nonprescription Chinese medicine.