Objective To investigate the effects of adenanthin on telomerase of leukemia NB4-LR1 cells and relevant mechanisms. Methods NB4-LR1 cells were treated with different concentrations of adenanthin (0, 2, 4, and 6 μmol/L) for different periods of time (0, 6, 12, and 24 h). The expression of human telomerase reverse transcriptase (hTERT) protein was detected by Western blotting, and the expression of hTERT mRNA was detected by Real-time PCR. The RNA interference method was adopted to decrease the expression of peroxiredoxin Ⅰ (Prdx Ⅰ) in NB4-LR1 cells. Then the expression of hTERT protein was detected by Western blotting. hTERT was over-expressed in NB4-LR1 cells and the NB4-LR1-hTERT-GFP and NB4-LR1-GFP cells were treated with different concentrations of adenanthin (2 and 4 μmol/L). The variations of proliferation and viability of cells were detected by trypan blue exclusion assay. Results The results of Western blotting showed that adenanthin inhibited the expression of hTERT in a dosetime dependent manner. The expression of hTERT decreased after Prdx I was knocked down. Over-expression of hTERT in NB4-LR1 cells partially inhibited the toxic effect of adenanthin on cells, but could not inhibit cell differentiation induced by adenanthin. Conclusion Adenanthin inhibits the expression of telomerase through Prdx Ⅰ and contributes to the death of cells.