Objective : To investigate the effects of C-type lectin domain family 5，member A( CLEC5A) on the pro- liferation，apoptosis，and cell cycle of leukemia cell lines THP-1 and K562，and the underlying mechanism． Methods : The expression of CLEC5A in leukemia patients was investigated in the GEPIA database. Recombined plasmid containing CLEC5A was transfected into THP-1 and K562 cells for overexpression of CLEC5A．Small interfering RNA(siRNA) was used to knock down the endogenous CLEC5A in leukemia cells．CCK-8 and EdU assays were used to assess the leukemia cells proliferation．Flow cytometry was used to assess cell cycle．Flow cytometry was used to assess cell apoptosis under hydrogen peroxide( H2 O2 ) stress．The RNA sequencing( RNA-seq) and pathway enrichment analysis were used to analyze the signal pathways of significant enrichment of up-regulated or down-reg- ulated genes after knocking down CLEC5A gene．Protein expression levels of several members in AKT1 / mTOR and p53 signaling pathways were detected by Western blot assays. Results : CLEC5A was significantly up-regulated in bone marrow tissues of leukemia patients compared to the matched non-tumor tissues of healthy individuals．Knock- down of CLEC5A significantly reduced the proliferation(all P＜0. 01) and S phase progression(all P＜0. 05) ，and increased the apoptosis(all P＜0. 001) under H2 O2 stress，in THP-1 and K562 cells．Conversely，overexpression of CLEC5A significantly increased the proliferation(all P ＜0. 001) and S phase progression ( all P ＜0. 01) ，and re- duced the apoptosis(all P＜0. 01) under H2 O2 stress，in THP-1 and K562 cells．The uregulated genes were sig- nificantly enriched in AKT1-mTOR and other signal pathways after knocking down CLEC5A，while the down-regula- ted genes were significantly enriched in cell cycle signal pathways．CLEC5A in leukemia cells significantly reduced the genes expression levels of BAX and p53，and significantly induced the gene expression levels of BCL-2 and phosphorylation levels of AKT1 and mTOR proteins． Conclusion CLEC5A increases the cell cycle and proliferation and inhibits cells apoptosis in THP-1 and K562 cells，and the mechanism may be related to activating the AKT / mTOR and p53 signaling pathways.