Objective：To investigate the effect of the cytoplasmic domain of leukemia inhibitory factor (LIF) receptor ɑ submit, gp190CT3, on activation of the JAK/STAT3 signal transduction pathway and on promotion of leukemia cell HL60 differentiation into granulocytes. Methods: pcDNA3.0gp190CT3 was used to transfect CHO cells. Using immunofluorescent cytochemistry, RTPCR and flow cytometry techniques, we detected the expression of gp190CT3 gene and protein in the stablytransfected CHO cells. Then the stablytrasfected CHO cells were cocultured with HL60 cells and the morphological changes of the HL60 cells were observed, the levels of STAT3 phosphorylation and the expression of the cell surface antigen CD15 were also determined. Results: Expression of gp190CT3 gene was found in pcDNA3.0gp190CT3 transfected CHO cells and gp190CT3stablytransfect CHO cells were obtained. Compared with the untreated HL60 cells, the size of the cocultured HL60 cells was increased, the morphology was irregular and the level STAT3 phosphorylation and the expression of CD15 were increased. Conclusion: The LIF receptor ɑ submit gp190CT3 participates in the activation of JAK/STAT3 signal transduction pathway and regulates HL60 cell differentiation and proliferation.