To study the molecular mechanism of Jiangtang Xiaoke Granule contained serum in protecting β-cells through studying the effects of Jiangtang Xiaoke Granule (JTXK) contained serum on FoxO1 expression in INS-1 cell. Methods:Lentivirus transfection was used to prepare FoxO1-overexpressing INS-1 stable cell line, and the overexpression was induced by 2.5 μg/mL doxycycline for 12 hours. The cells were treated with 10% JTXK granule containing serum for 24 h. And normal rat serum was used as control. The morphological changes of cells were observed under high power microscope. MTT analysis was used to calculate cell viability. The glucose concentration in cell culture was detected by automatic biochemical analyzer. And the glucose consumption was calculated. ELISA analysis was used to examine insulin secretion. The expression levels of FoxO1 and P-FoxO1 were evaluated by western blot. And the expression levels of FoxO1mRNA were evaluated by quantitative real-time PCR (qRT-PCR). Results:The cells did not have significant differences in size and shape. And there was no difference in cell viability among three groups. The glucose consumption and insulin secretion were increased in JTXK group (P<0.01). At the same time, the results of western-blot and qRT-PCR showed that the expression of FoxO1 and FoxO1mRNA had no difference (P>0.05). However, the expression of P-FoxO1 was increased (P<0.05). Conclusion:JTXK granule cannot decrease the expression of FoxO1 of INS-1 cell, but can promote phosphorylation of FoxO1, so as to improve β-cell function.