The invention belongs to the technical field of farm chemicals, and relates to a composition comprising brevibacillus brevis TW and trichodermin for preventing soil-borne diseases of melons, fruits and vegetables. The composition is wettable powder, which comprises 1 billion to 100 billion CFU/g of brevibacillus brevis TW and 10 million to 10 billion CFU/g of trichodermin; and the composition also comprises other ingredients in percentage by weight such as: 1 to 40 percent of dispersant, 1 to 40 percent of wetting agent and the balance of filling materials. The composition has the advantages that: (1) a good effect on preventing verticillium wilt and root rot of strawberries and blight and damping-off of vegetables can be realized; (2) the lasting period for the verticillium wilt and root rot of strawberries and the blight and damping-off of vegetables is long, so the times of the drug application can be reduced, and the prevention cost can be reduced; and (3) the composition is micro-organism combined preparation, has no chemical residue and is safe to use.