Genetic diversity in the physicochemical properties and fine structures of seven cassava starches samples was studied. The apparent amylose content ranged from 24.8 to 27.6%. The whole branched starches showed significant differences in average hydrodynamic radius, ranging from 53.35 to 58.45 nm, while debranched starch exhibited differences in degrees of polymerization and height of both amylose and amylopectin peaks. The molecular size of amylose and amylopectin was positively correlated. The amount of short chains fa (6 ≤ X ≤ 12) and fb1 (13 ≤ X ≤ 24) had significant differences among the cultivars. Structure-function relation analysis indicated that the CPV and SB were mainly determined by amylopectin fine structures, BD, PTi and Tp and retrogradation properties were mainly determined by the amylose fine structure, while PTe and To were mainly affected by both amylose and amylopectin fine structures. The current findings will be helpful to improve the understanding cassava starch quality for use in industrial starch applications.