Objective To explore the effect of clinical pharmacist on clinical rational use of antineoplastic drugs after participating in treatment group.Methods Retrospective research was used.According to whether there was a clinical pharmacist directly or indirectly involved in,all medical teams of the oncology department were divided into intervention group,advisory group and control group in our hospital.Intervention group was the medical team that had a specialist clinical pharmacist who could intervene irrational use of antineoplastic drug in the treatment on the spot.Advisory group was in the same area with the intervention group,and didn't have a specialist clinical pharmacist, but used to communicate with clinical pharmacist and take his medication advice,where clinical pharmacist indirectly involved in treatment.The control group was the medical group in the other area without clinical pharmacists of oncology department.The control group one and two were with the most beds among the control group.Randomly selected lung cancer,breast cancer,esophageal cancer,gastric cancer,colorectal cancer,gynecological cancer,liver/gallbladder/pancreatic cancer and other tumors patients from intervention group,advisory group,control group one and control group two,from January 2015 to December 2015,10 copies of each case,80 copies of each group.And antineoplastic drugs were commented specially.The information such as sex,age,clinical diagnosis,irrational antineoplastic drug use,adverse reaction and unexpected events and hospitalization time were recorded.Results The rate of irrational antineoplastic drug use of the intervention group (41.25%)was lower than the advisory group(80%),and was significantly lower than two control groups(147.50%,161.25%),advisory group was also lower than two control groups,but no significant differences between the two control groups(χ2 =0.193,P>0.05).Irrational chemotherapy, inappropriate usage and dosage and inappropriate indications were prominent problems in intervention group and advisory group.In addition,there were more improper solvent and contraindicated or adverse interaction problems in two control groups.Adverse events and incidence of unexpected events in intervention group (46.25%,12.50%) were significantly lower than those in two control groups[(73.75%,22.50%),(23.75%,18.75%)].Furthermore, the length of stay of intervention group patients was shortest in four groups (F=8.766,P<0.05).Conclusion By participating in the treatment group,clinical pharmacists can discover the irrational drug use and security risks in treatment,can provide medication guidance,consultation,publicity and other pharmaceutical service for specialist medical staff and patients.They will be more and more prominent in the treatment of cancer.