Abstract: According to the investigation of the damage range and the increase rate of Cuscuta japonica, the occasional, common and main host garden plants were identified, the incidence rate and damage degree of main host plants were determined, and the adaptive growth relationship between C. japonica and the main host plants was analyzed. The results showed that: (1) The damage range of C. japonica was constantly expanding, and the infection rate of trees, shrubs and ground cover were significant different, but they all increased year by year (P<0.05). (2) There were 41 species of plants belonging to 35 genera and 28 families invaded by C. japonica, among which 12 were occasional hosts, 19 were common hosts and 10 were main hosts (3 trees, 2 herbs and 5 shrubs). (3) The incidence rate and injury degree of main hosts were significantly different among species and years (P<0.05), and the symptoms and associated diseases of different hosts were significantly different. (4) The effects of C. japonica on the growth of leaves and young stems and the number of new branches of the host plants were significantly different. Host plants had significant effects on the growth and reproduction of C. japonica, and there was a significant adaptive growth relationship between C. japonica and host plants.