Abstract: Objective　To discuss the role of forkhead box O1 (FoxO1) in the injury and apoptosis of podocytes induced by homocysteine (Hcy). Methods　Ten Cbs+/+ mice with normal cysteine β -synthase (Cbs) gene and 10 Cbs+/- mice with single gene knockout were fed a high methionine diet. After 8 weeks, the mice were sacrificed to collect kidney tissues. Morphological changes of glomerulus were observed by PAS staining. Podocytes were cultured in vitro and divided into the control group and the Hcy group (treated with cell culture medium containing 80 μmol/L Hcy for 48 h). Podocytes were transfected with Ad-FoxO1 overexpressed adenovirus and Sh-FoxO1 interfering adenovirus carrying green fluorescent protein (GFP), and they were divided into the control group, the Ad-GFP group, the Ad-FoxO1 group, the Sh-NC group, the Sh-FoxO1 group, the Ad-GFP+Hcy group, the Ad-FoxO1+Hcy group, the Sh-NC+Hcy group and the Sh-FoxO1+Hcy group. Western blot assay was used to detect the expression of Podocin and Nephrin, FoxO1 and apoptosis-related B lymphocytoma-2 (Bcl-2), Bcl-2 associated X protein (Bax) and cystine proteinase 12 (Caspase12) proteins in renal tissues and podocytes of mice. The expression of FoxO1 mRNA in mouse kidney tissue and podocytes was detected by qPCR. Results　PAS staining results showed that the glomerular structure was normal, the basement membrane was clear and distributed evenly in Cbs+/+ mice, while the glomerular basement membrane presented intermittent thickening and the mesangial matrix increased in Cbs+/- mice. Compared with Cbs+/+ mice, the expression levels of Podocin, Nephrin and FoxO1 protein and FoxO1 mRNA were significantly decreased in Cbs+/- mice (P＜0.01). Compared with the control group, the expression of FoxO1 protein and mRNA in podocytes were significantly decreased in the Hcy group after treated with Hcy (P＜0.01). After overexpression of FoxO1 in podocytes, compared with the Ad-GFP+Hcy group, the protein expression of Podocin and Nephrin were significantly increased, both the ratio of Bax/Bcl-2 and the protein expression of Caspase12 were significantly decreased in the Ad-FoxO1+Hcy group (P＜0.05). After FoxO1 interference, compared with the Sh-NC+Hcy group, Podocin and Nephrin protein expressions were significantly decreased, Bax/Bcl-2 ratio and Caspase12 protein expression were significantly increased in the Sh-FoxO1+Hcy group (P＜0.05). Conclusion　FoxO1 can reduce Hcy-induced renal podocyte injury and apoptosis in mice.