[Objective] To determine the optimum induction method, different induction methods on Agrobacterium tumefaciens EHA105-mediated transformation system of Trichoderma harzianum T88 were investigated. [Methods] By comparing the conversion efficiency of double cultivation, blotting cultivation and liquid co-cultivation, the optimum induction method can be determined. [Results] The conversion efficiency of double cultivation is about 10 transformants per 107 conidia, the conversion efficiency of blotting cultivation is about 20 transformants per 107 conidia, while the conversion efficiency of liquid co-cultivation is about 100 transformants per 107 conidia. [Conclusion] The conversion efficiency of liquid co-cultivation is the maximum in A.tumefaciens-mediated transformation system of T. harzianum, it is about 5?10 times of double cultivation and blotting cultivation.