In order to describe the biological characteristics of Catalpa fargesii f.duclonxii leaf spot pathogen (Glomerella cingulate),and to select suitable fungicides against it, the mycelial growth in different conditions were observed,and the fungicides against the pathogen were investigated in this paper. The results indicated that the pathogen mycelia grew well under 21-28 ℃, pH 4-7, and the lethal temperature was 45 ℃.Optimal carbon and nitrogen source were sucrose and NaNO3 respectively. The most effective fungicide was 10% difenoconazole among the 5 tested reagents, and the relative inhibition rate was 93.6% with the recommended concentration.