Objective　To set up a 3D digital model of hallux valgus and provide theoretical support for Ludloff osteotomy in patients with hallux valgus to reduce the operation risk, increase the operation safety and improve the curative effect  by simulating Ludloff osteotomy, comparing the changes of preoperative and postoperative parameters, predicting the postoperative curative effect and complications Methods　11 cases of patients (13 feet)with hallux valgus who treated at department of foot and ankle surgery, Guangzhou orthopaedic hospital from January 2016 to January 2017 were retrospectively collected. A 3D digital model of the foot was set up based on CT data. 3D construction model was simulated to measure and statistically analyze the preoperative and postoperative the hallux valgus angel ( HVA), the intermetatarsal angel from the first to the second metatarsal (IMAI~II), the length of the first metatarsal, the relative length of the second metatarsal and the intermetatarsal angel from the first to the fifth metatarsal (IMAI~V).　Results  Preoperative and postoperative simulating osteotomy of HVA , IMAI~II, length of the first metatarsal, the relative length of the second metatarsal, IMAI~V were (35.62±6.54) °and (35.62±6.54) °, (16.43±2.41)°and (9.12±3.18）°, (63.58±4.17)mm and (59.87±3.83)mm,  (93.74±6.02)°and (86.85±5.36)°, (29.68±3.65)°and (19.45±2.46)°respectively. There were statistical significance of the above corresponding indicator changes of before and after simulating osteotomy (P<0.05).　Conclusions　Using 3D digital model technique to simulate Ludloff osteotomy and measure the parameters is a feasible way to evaluate the effect of Ludloff osteotomy and provide reference for formulating the operative plan.