This paper theoreticaly explore the irrational drug mechanism of action, in order to explore the irrational prescription drug problems, and discuss measures to improve the problem of irrational use of drugs found in drug dose is too large, the existence of incompatibility intravenous drugs, intravenous medications. the solvent is not enough and adverse drug interactions and therefore irrational drug problems prevalent in prescription, physicians and pharmacists must focus on improving the level of their business in order to improve the quality of medication.