Abstract: Six rice cytoplasmic male sterile lines were crossed with 10 early-seasoned rice restorer lines by incomplete diallel cross(NCⅡ)design to make 60 combinations of early-seasoned hybrid rice. Twelve agronomic characters of these parents and their hybrid combinations were observed for genetic analysis. The results obtained showed that the additive effect was predominant for all the characters. The paternal effect was greater than maternal one for all the characters except spikelet length. The narrow heritability of each character was arranged in descending order as 1000-grain weight, plant height, spikelet length, plump seeds per spikelet, seed set, total seeds per spikelet, whole growth period, expected grain yield, observed grain yield, effective spikelet number, effective spikelet percentage and maximum tiller number. The expected grain yield was positively correlated with seed set, plump seeds per spikelet, plant height, effective spikelet percentage and effective spikelet number, which could be used for indirect selection for yield. The character plump seeds per spikelet was the most important among components of yield selection index in early-seasoned hybrid rice.