Abstract: The relationships among the nutrition,temperature,relative humidity,solar radiation and other biological factors and the hypha growth of E.parasitica were studied in order to understand the biological characteristics of the fungus and to provide the effective control and mitigate the damage of chestnut disease with scientific evidence.The results obtained were as follows: PDA was the optimal medium for the hypha growth of E.parasitica.The optimum temperature for the hypha growth was 30 ℃,and the most suitable relative humidity was 90%~100%,whereas the solar radiation condition did not make evident difference.Temperature and relative humidity were the key elements among the above discussed ecological factors.