The performances of major agronomical characters of F₃ populations and their relationships with parents, F₁ and F₂ were studied. The results indicated that the degree of dominance was gradually weakened with the advance in generations. The average performances of F₃ populations were closely correlated with that of parents or mid-parent for major agronomical characters. Among the characters studied, the correlation coefficients of 1000-grain Weight of different generations with that of the parents or mid-parent were scarcely different. The grain weight per spike of F₃ was determined by the length of spike, number of grains per spike and 1000-grain weight,among which the contribution of the number of grains per spike was the largest. The heritabilities of 1000-grain weight and the length of spike were the highest, while that of grain weight per spike was the lowest. The character of 1000-grain weight could be selected in F₃ generation. The. number of grains per spike and grain weight per spike should be selected with bulk method in F₂ and F₃. Pedigree method should be applied after F₄ generation.