Through the random sampling method，the main species，harm object and damage degree of garden plant defoliator of Harbin city were investigated.The results showed that the Harbin city garden defoliating insects belongs to 3 orders，12 families,17 kinds coming from Lepidoptera，Coleopteran and Hymenoptera;of which Lepidoptera was the most,induding 8 families，12 species，which accounting for 71%；Coleopterans was secondly,including 2 families，3 kinds，accounting for 18%；Hymenoptera was at least，including families，2 kinds.Defoliating insects control guidelines and strategy of Harbin garden plant were put forward.