Objective To compare the efficacy of proximal femoral varus osteotomy alone and proximal femoral varus osteotomy combined with steel osteotomy in the treatment of severe Legg–Calvé–Perthes disease. Methods Patients with severe Legg–Calvé–Perthes disease in our hospital from January 2013 to June 2021 were retrospectively analyzed. According to the surgical method, the patients were divided into simple proximal femoral varus osteotomy group (Femoral group) and proximal femoral varus osteotomy combined with steel osteotomy group (Combined group). The operation time, intraoperative blood loss, acetabular index (AI), acetabular angle (Sharp angle), lateral center-edge angle(LCEA), femoral head extrusion index (FHEI),Harris hip score, ROM and Stulberg classification at last follow-up were recorded and compared between the two groups. Results A total of 38 patients were enrolled, including 17 patients in femoral group and 21 patients in combined group. The average age was 8.2±3.4 years; 29 males and 9 females; 6 cases of modified Herring type B, 15 cases of B/C type and 17 cases of C type; The follow-up time was 33.0±9.6 months. Satisfactory healing was achieved at the operative site and osteotomy end. The operation time and blood loss in the femoral group were less than those in the combined group. There was no significant difference between the two groups in Harris hip joint score, ROM and Stulberg typing results in the last follow-up (p>0.05). The AI, FHEI and Sharp angle of the two groups decreased, and the LCEA increased. There was a statistically significant difference between the two groups (p<0.05). Conclusions The combined group can better achieve the inclusion effect of the femoral head and promote the recovery of the femoral head than the femoral group, but the surgical trauma is greater.