OBJECTIVE： To design Proton pump inhibitor （PPI） medical order evaluation software， and to promote rational drug use in clinic. METHODS： According to the use of PPI （PPI injection as an example） of inpatients in a Third Grade Class A hospital （hereinafter referred to as "sample hospital"）， the evaluation process of medical order evaluation software was designed. On this basis， medical order evaluation software for inpatients was developed in collaboration with computer engineers. Taking the detection rate of irrational drug use and the time consuming per capita as indicators， the effects of software evaluation and manual evaluation were compared. Dispensing medical orders of PPI injection in PIVAS of sample hospital was evaluated with the software pre-evaluation in Feb. 2018. Irrational use of PPI injection （including irrational medication for treatment， prevention and non-indication） in the inpatients was evaluated retrospectively during Jan. 2015-Dec. 2017. RESULTS： The software of PPI audit includes four modules：users and tasks （timing audit）， system settings， confirmation of audit results （check the results audited by the software automatically） and reports exporting. Compared with manual evaluation， there was no significant difference in detection rate of irrational drug use in software audit （69.50％ vs. 77.00％， P＞0.05）； the time consuming per capita was shortened significantly （9.25 min vs. 1.50 min， P＜0.05）. In the application of pre-evaluation， 27 （2.23％） were irrational for treatment， 318 （26.24％） were irrational for prevention and 602 （49.67％） for non-indications. In the application of retrospective review， 4 884 （2.68％） were irrational medication for treatment， 50 399 （27.67％） irrational medication for prevention and 85 106 （46.72％） medication without indications. CONCLUSIONS： The application of PPI medical order evaluation software shortens the time of pharmacist's evaluation， improves the efficiency of evaluation， and promotes the rational use of PPI in clinic.