〔Abstract〕 Objective To explore the effect of hydroxy-carboxylic acid receptor 2(HCAR2) on erythroid differentiation of human chronic myeloid leukemia K562 cells under hypoxia. Methods The cells were cultured in medium containing hemin to compare the ability of K562 cells to differentiate into erythroid cells under normoxia/hypoxia conditions. Then the expression of HCAR2 was interfered with genetic methods to knockdown or overexpress it in K562 cells, respectively. Benzidine staining, RT-qPCR, Western blot and flow cytometry were used to detect the role of HCAR2 in the erythroid differentiation of K562 promoted by hypoxia. Results On day 1, 2, 3 after differentiation, the expression level of HCAR2 and the erythroid differentiation ability of K562 cells increased gradually with time, and hypoxia enhanced the above phenotypes compared with normoxia. In HCAR2-silenced K562 cells, erythroid cells was reduced and the expression of erythroid differentiation markers CD235a and γ-globin decreased. Simultaneously, the proportion of double-positive cells expressing erythroid cell surface molecules CD71 and CD235a was lower than that of the control group. On the contrary, the overexpression of HCAR2 in K562 cells increased erythroid cells generation as well as elevated the expression levels of CD235a and γ-globin. In addition, the proportion of CD71/CD235a double-positive cells also increased in HCAR2-overexpressed K562 cells. Conclusion HCAR2 mediates hypoxia in promoting the erythroid differentiation of K562 cells.