To investigate the function and mechanism of GINS complex subunit 2 (GINS2) in osteoblast and osteoclast in steroid-induced osteonecrosis of the femoral head (SINFH). Clinical specimens were collected from 40 cases of SINFH patients and 40 cases of control patients. Then, SINFH mouse model was built. Immediately, osteoblasts and osteoclasts were induced and differented from the pre-osteoblast cell line MC3T3-E1 and the mononuclear macrophage cell line RAW264.7 of mice, respectively. The qRT-PCR assay was used for detecting the expressions of GINS2, p53 and growth arrest and DNA damage 45A (GADD45A). The cytoactive, proliferation and apoptosis of osteoblasts and osteoclasts of SINFH mice were measured by tartaric acid phosphatase staining, CCK-8 and Annexin V-FITC/PI dual staining, respectively. GINS2 was up-regulated while p53/GADD45A was down-regulated in femoral tissues in SINFH patients and mice. GINS2 was down-regulated while p53 and GADD45A were up-regulated in osteoblasts of SINFH mice, which presented opposite trends in osteoclasts formations. GINS2 decreased osteoblasts activities and increased osteoclasts activities, inhibited apoptosis and promoted proliferation in osteoblasts and osteoclasts via p53/GADD45A pathway. GINS2 affects activity/differentiation, apoptosis and proliferation of osteoblast and osteoclast in steroid-induced osteonecrosis of the femoral head by regulating p53/GADD45A signaling pathway.