OBJECTIVE： To discuss the application of rational drug use software system in drug dispensing in outpatient department of our hospital. METHODS： The application of rational drug use software system （included clinical decision support software， drug dispensing software and drug management software） in prescribing （warning in advance）， dispensing （intervention in the event） and the prescription review （the post review） in outpatient department of our hospital were all introduced. Outpatient prescription checking and intervention were collected from our hospital after the application of rational drug use software system to evaluate the effect of the software system. RESULTS & CONCLUSIONS： Rational drug use software system is adopted to realize scientific， convenient and express monitoring and management of prescription drug use in advance， in the course and afterwards. A total of 721 507 outpatient prescriptions were checked in our hospital from Jan. to May in 2015； 0.17‰ prescriptions were intercepted by system warning； system pointed out and pharmacists had checked 23.25％ prescriptions； the rate of qualified prescription was more than 99.96％. After pharmacists intervention， various types of irrational prescriptions decreased significantly （P＜0.01）. It is suggested that pharmacists should make full use of information system， at the same time， optimize and improve the system through active exploration so as to improve rational drug use.