Objective To evaluate the clinical effects of modified Danggui Buxue Decoction in the treatment of postoperative posterior lumbar internal fixation.Methods According to digital table method,60 patients with lumbar spinal stenosis who underwent posterior decompression and internal fixation were randomly divided into treatment group and control group with 30 in each group.The treatment group was given conventional antibiotic therapy and modified Danggui Buxue Decoction after surgery.The control group was only given conventional antibiotic therapy after surgery.The clinical manifestations,drainage volume,temperature VAS score,Hgb and RBC were compared between two groups before and after the treatment.Results The drainage volume,max temperature,the VAS score,Hgb on day 1 and day 3 and RBC on day 1 were no statistically significant（P>0.05）;The average fever days,Hgb on day 10,RBC on day 3 and day 10 were statistically significant（P<0.05）.Conclusion For the postoperative posterior lumbar internal fixation,modified Danggui Buxue Decoction can surely improve anemia and shorten fever time.