Objective:To observe the expression of interleukin (IL)-25 in asthmatic mice and to investigate the potential influence of IL-25 on release of IL-6 in mast cells. Methods: BALB/c mice aged 6-8 weeks were randomly divided into the control group and the asthma group, and treated with equal amount of phosphate buffer solution (PBS) or ovalbumin (OVA), respectively. Mouse asthma model was validated by detecting the total number of cells and eosinophil cells (EOS) in bronchoalveolar lavage fluid (BALF). The expressions of IL-25 mRNA in lung tissues and IL-25 in BALF and serum were measured by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) in the two groups. Mouse P815 cells were divided into the control group and the IL-25 group, and treated with equal amount of culture medium or IL-25, respectively. The levels of released IL-6 in supernatants were detect by ELISA. Results: In BALF, the total number of cells and EOS in the asthma group were significantly increased than those in the control group (P < 0.01). The mice were irritable and their breathing rate were accelerated, and the model was validated. The expressions of IL-25 mRNA in lung tissues and IL-25 in BALF and serum were significantly higher in the asthma group than those in the control group (P < 0.01). In P815 cell supernatants, the secretion of IL-6 in the IL-25 group were significantly higher than those in the control group (P < 0.01). Conclusion: The expression of IL-25 was increased in OVA-induced mouse asthma model. IL-25 may promote the process of asthma by stimulating IL-6 release from mast cells.