Abstract: This paper shows that the conidia maintained their germinating ability for 15 days,the aggressiveness for 13 days.The optimum temperature for the germination of conidia was 25℃,the best relative humidity 100%.Sugar solution,extract of the host's leaves and some diffused light favoured the germination of conidia.In addition,it was found that paecilomyccs sp. could parasite on the conidia.After crapemyrtle being infected,the content of chlorophyll was reduced,photosynthetic capacity was lowered,the carbohydrate metabolism was disordered,however,the transpiration and content of polyphenol was raised.