[Objective] To study the effect of high tibial osteotomy (HTO) combined with platelet-rich plasma (PRP) in the treatment of knee osteoarthritis. [Methods] Totally 88 patients with knee osteoarthritis in the hospital were randomly divided into osteotomy-alone group (n=29), PRP-alone group (n=31), compound group (n=28). Operation time, fluoroscopic times and time to walk were recorded and compared in each group. Visual pain scale (VAS), range of motion (ROM) and KOOS knee function score were performed preoperatively, 3, 6 and 18 months postoperatively, and imaging evaluation was performed. [Results] There were no significant differences in incision length, intraoperative blood loss and fluoroscopic times among all groups (P >0.05), but there were significant differences in operative time, hospitalization cost and length of stay among all groups (P <0.05). VAS, ROM and KOOS scores of each group showed a trend of significantly improvement over time (P <0.05). At the same time point, the scores of the compound group were better than those of the other two groups, and there were significant differences at 6 months after surgery (P <0.05). At the last follow-up time, there were no significant differences between the composite group and the HTO group (P >0.05), but there were statistically significant differences between the composite group and the PRP group (P <0.05). After osteotomy, all the groups had femorotibial angle (FTA), medial and proximal tibial angle (MPTA), and posterior tibial slope(PTS) were significantly improved (P <0.05), but there was no significant difference between groups (P >0.05). Kellgren Lawrence grading of medial ventricle (K-L) was improved, but there was no statistical significance (P >0.05). [Conclusion] HTO combined with PRP in the treatment of knee arthritis has advantages in early postoperative clinical effect, which can significantly improve the function of knee joint and relieve patients' pain.