Abstract: [Objective] To introduce the surgical technique and preliminary clinical results of 3D printing-assisted one-stage osteotomy and total knee arthroplasty for complex lower limb deformities. [Methods] Six patients with complex lower limb deformities were treated in Fuyang people's Hospital and the second affiliated Hospital of Anhui Medical University from May 2015 to November 2019. The CT data were imported into the computer. According to the situation of extraarticular deformities, the force lines of lower extremities were simulated and corrected by osteotomy. The osteotomy guide plate and the corrected verification guide plate were designed, and then the osteotomy guide plate for TKA was designed. During the operation, 3D printing guide plate was used to assist correction of extraarticular deformity and total knee arthroplasty. [Results] The average follow-up time was 36 (24 ~ 76) m, the operation time was 4.5 (2.5 ~ 5.0) h, and the perioperative blood loss was 400 (250 ~ 520) ml. The postoperative overall deformity angle (ODA), HKA and MAD were 2.64° ±0.65°, 179.40° ±0.89° and 3.80 mm ±2.39 mm respectively, which were significantly better than those before operation (34.03° ±4.26°, 155.67°± 10.25 °, 16.33mm ±2.80mm). KSS and ROM at the last follow-up were significantly better than those before operation. [Conclusion] 3D printing-assisted one-stage osteotomy and total knee arthroplasty is beneficial for precise osteotomy and orthopedics, and the preliminary clinical effect is good.