Abstract: Four Trichoderma species, Trichoderma viride, Trichoderma koningii and two unidentified Trichoderma species, in dual culture with Verticillium dahliae were studied and the non-volatile antibiotics which inhibited the dry weight of mycelium Verticillium dahliae were tested. The inhibitory activity against Verticillium dahliae was also studied based on their dual culture and secondary metabolites.The results showed that four species of Trichoderma spp.could significantly inhibit in the dual culture. The non-volatile antibiotics inhibited very strong the growth of Verticillium dahliae. The dry weight of mycelium was evidently less than that of the control and the non-volatile antibiotics were not sensitive to the heating. The light microscopy (LM) investigations showed that Trichoderma species appeared to inhibit pathogens by mycoparasitism, with evidence of either parallel or waved growth, and led to hyphal cell cytoplasm concentration and disruption. The experiment evidence was provided for looking for effective biocontrol on Trichoderma species and Verticillium dahliae.