Abstract: In 2019, damage by Lymantria dispar was first found in Hangzhou, Zhejiang province. During 2020 and 2021, investigations were carried out on the characteristics of occurrence and damage, biological properties and natural enemies. The result showed that L. dispar occurred in the forest at the junction of Xihu, Fuyang and Yuhang district in Hangzhou, feeding on broad-leaved plants such as Quercus acutissima with high population density. It has one generation a year, hatches in late March, pupates from late April to late May, emerges from early May to early June, and overwinters by eggs. It damages many important ecological and economic tree species in Zhejiang. Glyptapanteles liparidis, Drino inconspicua and L. dispar Multiple-embedded Nucleopolyhedrovirus（LdMNPV）were three important natural enemies in this area, with parasitism or infection rate of 36.54%, 40.38% and 58.93%.