Abstract: The aim of this two years research work is to recognize bio control agents and its antagonistic efficiency on Sclerotium rolfsii in vitro condition. Sclerotium rolfsii Sacc. is a causal agent of white foot and root rot disease in many plants. This fungi causing damage in tea nurseries of tea cultivated countries especially in Iran. Due to importance this disease in tea nurseries of Iran and impossibility using of chemical control against this damaging agent In this research, five species of Trichoderma viride, Trichoderma harzianum, Trichoderma hamatum, Trichoderma longibrachiatum and Trichoderma parceramosum as antagonist fungi against Sclerotium rolfsii were collected and identified from tea nurseries and seedlings in Iran. Then efficiency of these bio control agent against Sclerotium rolfsii were investigated in vitro condition. Results showed that these species with different mechanism such as lysis of sclerotia, inhibited mycelial growth of Sclerotium rolfsii with volatile metabolites producing and parasitized the hyphal trends of disease agent were showed its antagonistic effects against causal agent of white foot and root rot in tea seedling. Trichoderma viride, Trichoderma harzianum and Trichoderma hamatum after 30 days destructed and lysis the sclerotia 98.5, 86.5 and 85%, respectively. Producing of volatile metabolites after 72 h reciprocal growth of Trichoderma viride, Trichoderma harzianum and Trichoderma longibrachiatum till 60.8, 54.8 and 54.4% prevented mycelium growth of Sclerotium rolfsii, respectively. All identified species caused parasitize (to hyphal contact method) pathogen fungal hypha that the first three species showed more parasite effect.