The invention discloses trichoderma spp for prevention and treatment of watermelon fusarium wilt and an application thereof. Therefore, the trichoderma spp provided by the invention is obtained by isolating and screening soil of watermelon planting fields in Huaiyuan County, Anhui Province and carrying out ray mutagenesis, and is preserved in China Center for Type Culture Collection on May 23, 2019 with the preservation number of CCTCC NO.M2019337. The trichoderma spp strain has obvious prevention and treatment effect on watermelon fusarium wilt, strong disease resistance, bacteriostasis and continuous cropping resistance effects, and obvious characteristics on improving the watermelon yield and taste, not only can improve soil and reduce the use amount of chemical fertilizers and pesticides, but also can reduce the input of farmers and increase the income of the farmers, and plays a positive role in environmental pollution control.