One of the most important tomato diseases is the Damping off disease. The cause of this disease is Fusarrium oxysporum. It is one of the most common diseases of tomato, which causes a lot of economic damage every year. The disease has a wintering and shelf life in the soil and plant remains, which, by providing the appropriate temperature and humidity conditions, are introduced into the plant tissue through rooting. Trichoderma spp. are among the living factors that control the plant diseases and induce resistance to plants, One of the most important species of this fungus is Trichoderma harzianum. In this study, two strains of this biocontrol species i.e. of T-22 (commercial) and AS12-2 (native Iranian strain) were used. Commonly used copper fungicides such as BordeauxFix and Copper chloride oxide hydrate are used to control the disease. In order to investigate the effects of these fungicides on Trichoderma as a biological control agent and Fusarium as a causative agent, three fungi were exposed to 7 different concentrations of two fungicides, and the results were as follows: in Fusarium the most effective dose of Copper chloride oxide hydrate and BordeauxFix was observed at a concentration of 0.5 mg 100 mg of active ingredient per liter, respectively. Intrestingly, AS12-2, was more resistant to the two fungicides than T-22. These two biocontrol strains could tolerate up to 2000 mg of active ingredient per liter and also they showed more tolerance to Copper chloride oxide than BordeauxFix. The results of these experiments showed that if the appropriate concentrations of these fungicides were used, the beneficial fungi would not damaged, and simultaneously chemical and biological control could be used together.