To research the possible mechanism of Yiqi Yangyin Formula（ Qi-Boosting Yin- Nourishing Formula） for acute myeloid leukemia（ AML）. Methods Forty nonobese diabetic / severe combined immunodeficient（ NOD-SCID） mice were irradiated with60Co and induced into AML models with tail vein injection of 1 × 106KG1a cells. The models were randomized into four groups with 10 in each. The model group was gavaged with normal saline. The vital qi-supporting group was gavaged with 1. 08 g / ml concentrated solution of vital qi-supporting formula. The evil-dispelling group was gavaged with 0. 92 g / ml concentrated solution of evil-dispelling formula. The entire formula group was gavaged with 2 g / ml concentrated solution of entire formula. Each group was gavaged with 0. 2 ml solution / each time

twice daily for 28 days. The telomerase activity in bone marrow cells was detected with PCR-ELISA method. The methylation and expression of human telomerase reverse transcriptase（ hTERT） mRNA and its promoter were detected with quantitative PCR. Results Comparing with the model group

the activity of hTERT and the methylation and expression of hTERT mRNA and its promoter was significantly decreased in the vital qi- supporting group

evil-dispelling group and entire formula group（ P < 0. 05 or P < 0. 01）

especially in the entire formula group（ P < 0. 05 or P < 0. 01）. Conclusion Yiqi Yangyin Formula can treat AML by reducing the activity of hTERT and the methylation and expression of hTERT mRNA and its promoter.