Abstract: The solubility parameters of azo and anthraquinone disperse dyes, which are usefulfor the elucidation of polyester dyeing behavior, were calculated by the Small's, Hoy's,Krevelen's and Fedors' group molar constant methods. Some of the Small's molar attra-ction constants were extended. Results from Hoy's method are more preferable. Somerelationships have been found: (1) When the solubility parameters of those dyes close tothat of polyester fiber, the sublimation fastnesses may reach 4-5 grade; (2) Dyeing level-ness increases almost with decreasing molar volume; (3) Diffusion coefficient increaseswith decreasing molar volume and the tendency becomes level slowly.