Abstract: In order to study the cold tolerance of ornamental plants of the genus Chaenomeles, three different types of Chaenomeles trees were selected as research objects, and their water content, starch content, soluble sugar, and peroxidase（POD）, superoxide dismutase（SOD） and relative conductivity and other physiological and biochemical indicators from September to January of next year. Then the Logistic equation was used to solve the semi-lethal temperature, and the membership mean was calculated by the subordination function method to comprehensively evaluate its cold resistance. The results showed that with the increase of cold resistance, the soluble sugar content, POD activity and SOD activity all increased, and the change trend was the same as that of cold resistance. The cold resistance of the stems of the three tree species was Chaenomeles japonica （Thunb.） Lindl. ex Spach<Chaenomeles speciosa （Sweet） Nakai<Chaenomeles sinensis （Thouin） Koehne.

Key words: Chaenomeles, ornamental plant, cold tolerance, Logistic equation