Abstract: Objective：To understand the general situation of unreasonable drug use in outpatient and emergency prescriptions of our hospital， and analyze the causes of unreasonable drug use， so as to provide references for clinical rational drug use. Methods： Outpatient and emergency prescriptions of our hospital from January to December in 2018 were collected， and unreasonable prescriptions were classified. Pareto diagram was used to analyze the main factors， secondary factors and general factors. Results：The main factors of unreasonable drug use in outpatient and emergency prescriptions of our hospital were incomplete writing in clinical diagnosis and inappropriate usage and dosage. The secondary factor was the use of antibiotics without indication. The general factors were repeated drug use， class Ⅱ psychotropic drugs over 7 d， off-label drug use， inappropriate indications， contraindication medication， inappropriate drug delivery route. Conclusion：Pharmacists should make effective intervention according to the factors of unreasonable drug use， improve the level of rational drug use and ensure the quality of pharmaceutical care.