Abstract: In order to improve application of Trichoderma harzianum on the production of muskmelon, in vitro and pot experiments were carried out to examine the inhibitory effect, resistance against Fusarium oxysporum f.sp. melonis（FOM） treated with Trichoderma. In vitro experiments indicated that T. harzianum and its volatile compounds and fermentation broth inhibited the growth of FOM mycelium, the inhibitory rate was 77.18%, 18.73% and 22.79%, respectively. The pot experiments results showed that T. harzianum could alleviated the incidence of Fusarium wilt, and improved the activity of PAL and β-1,3-glucanase in muskmelon root and seedling. In conclusion, T. harzianum DQ002 significantly inhibited the growth of the pathogen of Fusarium wilt through space competition and its fermentation broth and volatile substances, and improved the PAL and β-1,3-glucanase activity, enhanced the resistance of muskmelon to Fusarium wilt and reduced the incidence of melon Fusarium wilt.