Abstract: [Objective] To explore the clinical efficacy of the cup on cup technique in the revision total hip arthroplasty (THA) for Paprosky type Ⅲ acetabular bone defects. [Methods] A retrospective study was conducted on 21 patients who had Paprosky type Ⅲ acetabular bone defects treated with the cup on cup technique used in revision THA in our hospital from January 2021 to December 2022. The clinical and imaging documents were evaluated. [Results] All patients had the revision THA performed successfully with the average operation time of (106.2±19.5) min, the average intraoperative blood loss of (320.4±140.2) mL, and the average incision length of (163.2±17.8) mm. The average follow-up period lasted for (13.5±4.5) months in a mean. Compared with those before the operation, the VAS scores [points, (7.5±0.9), (2.5±0.8), (1.6±0.5), P＜0.001] were significantly decreased, while the Harris score [points, (33.5±6.1), (74.0±5.6), (79.6±3.1), P＜0.001], hip flexion-extension ROM [°, (59.0±15.6), (105.7±7.6), (109.7±6.2), P＜0.001], hip internal-external rotation ROM [°, (11.9±2.9), (33.1±4.0), (34.7±3.3), P＜0.001] were significantly increased 3 months after operation and at the last follow-up. As for imaging, compared with those before operation, the acetabular abduction angle and acetabular anteversion were significantly improved (P＜0.05), while the leg length discrepancy was significantly reduced 3 months postoperatively and at the latest follow-up (P＜0.05). [Conclusion] The cup on cup technique has definite clinical efficacy in revision THA for Paprosky type Ⅲ acetabular bone defects, and can restore hip function early.