[Objective] This study aimed to investigate the expression of recombinant protein of fibroblast growth factor 21 (FGF21) in Escherichia coli induced by lactose and explore the possibility of engineering production.[Method] The effects of lactose concentration, induction duration, induction starting time, and induction temperature on expression of the recombinant product were compared, and the optimal condition for lactose induction was determined with IPTG induction as a control.[Result] As an induction agent, lactose plays an ideal role in the production of recombinant FGF21. In addition, the expression level of lactose induction product is consistent with that of IPTG induction product. Induction in a 250ml flask containing 50ml of medium at A600 0.8-1.0 using 0.5g/L lactose at 35℃ for 6h are the optimal condition.[Conclusion] Lactose can induce the expression of FGF21 gene and achieve ideal results. This study provides experimental basis and reference for the industrial production of FGF21. [Objective] This study aimed to investigate the expression of recombinant protein of fibroblast growth factor 21 (FGF21) in Escherichia coli induced by lactose and explore the possibility of engineering production. [Method] The effects of lactose concentration, induction duration, induction starting time , and induction temperature on expression of the recombinant product were compared, and the optimal condition for lactose induction was determined with IPTG induction as a control. [Result] As an induction agent, lactose plays an ideal role in the production of recombinant FGF21. In addition, the expression level of lactose induction product is consistent with that of IPTG induction product. Induction in a 250 ml flask containing 50 ml of medium at A600 0.8-1.0 using 0.5 g / L lactose at 35 ° C. for 6 h are the optimal condition. ] Lactose can induce the expression of FGF21 gene and achieve ideal results. This study provides experimental basis and reference for the industrial production of FGF21.