To explore the basic rules of clinical application about eighteen incompatible medicaments contained in prescriptions in modern time. 1964 formulas were screened out of TCM journal databases and studied based on the method of frequency analysis and maximal frequent item sets mining. The result showed that the prescriptions existed in all kinds of clinical trials

and were mainly used to treat the difficult and complicated cases such as cardio-cerebrovascular disease

cancer

and so on. Clinical effects of some drug pairs were influenced by the dosage ratio and administration ways such as oral combined externally application. This systematic review provided valuable information on the evaluation of clinical safety about eighteen incompatible medicaments

and it might be helpful to provide scientific supports and instructions for the clinical practices of the related Chinese herbal medicine.