The invention relates to a trichoderma harzianum composite bacteria culture and application of the same in the aspect of plant protection, and belongs to the technical field of biology. The strain of the trichoderma harzianum composite bacteria culture is preserved in the China General Microbiological Culture Collection Center (CGMCC), and classified and named as Trichoderma harzianum MDCGTH 18, with a preservation number of CGMCC NO.2965. The Trichoderma harzianum MDCGTH 18 composite bacteria culture utilizes antagonistic microbes for biological prevention and treatment, simultaneously has the functions of inducing the disease resistance of plants and increasing the yield, has obvious effect of controlling aspen root rot, apple root rot, citrus yellow shoot, watermelon fusarium wilt, tobacco bacterial wilt, wheat scab, full rot, root rot, banded sclerotial blight, cucumber powdery mildew, downy mildew, vegetable gray mold, fusarium wilt and various other epidemic diseases, can be independently taken as a biological control microbial inoculum for plant diseases, and can also be mixed with other biological antiseptics, plant antibiotics, plant growth regulators and the prior antiseptics to prepare various biological antiseptics for controlling different plant diseases.