Abstract 【Aim】 Starvation is one of the main stress signals for organisms in their developmental cycle. The purpose of this study is to understand how the silkworm (Bombyx mori) adjusts the metabolism conditions to survive after starvation and to explore the role of forkhead box transcription factor O gene (FoxO) in this process. 【Methods】 The 5th instar day-2 larvae of B. mori were subjected to chronical starvation for 72 h, the contents of triglyceride and glycogen in the fat body and the concentration of trehalose in the hemolymph were measured every 12 h, and the expression levels of BmFoxO, insulin receptor gene (InR) and protein kinase B gene (Akt) of insulin pathway and genes related to lipid metabolism were detected in the fat body by qPCR. A vector overexpressing BmFoxO was constructed and transfected into BmE cells, and the expression levels of genes related to glucose and lipid metabolism in BmE cells were detected by qPCR. 【Results】 The contents of glycogen and triglyceride in the fat body of the silkworm larvae continuously decreased within 72 h after starvation, and the concentration of trehalose in the hemolymph increased during 48 to 72 h after starvation. qPCR results revealed that the expression levels of genes of insulin pathway such as BmFoxO, InR and Akt and those linked to lipid metabolism enhanced remarkably during starvation stress, accelerating lipolysis. After overexpression of BmFoxO in BmE cells, the genes BmFoxO, InR and Akt showed a similar expression trend to that in B. mori larvae under starvation stress. 【Conclusion】 BmFoxO can regulate the glucose and lipid metabolism, and participate in the resistance to starvation in the silkworm. This study provides a basis for further studying the function of BmFoxO in the growth and metabolism in the silkworm.