Abstract: Poor grain filling is one of the major constraints to increase yield potential of intersubspecific hybrid of rice.Genetic analysis of grain plumpness was conducted with a doubled haploid (DH) population derived from an indica/japonica cross in the present study.The results revealed that rice grain plumpness was a quantitative trait genetically controlled by polygenes.There were about 5～6 genes to segregate in the DHpopulation for the trait.Duplicate interactions among these genes were detected based on estimation of third and fourth statistics (skewness and kurtosis).Transgressive segregation was observed for grain plumpness,implying that pyramiding of the favorable alleles for grain filling could result from gene recombination.Rice grain plumpness was positively correlated with grain yield,number of filled grains per panicle,and the ratio of dry matter weight to capacity of sink at 5% or 1% levels,while not significantly with 1000-grain weight,number of spikelets per panicle,and capacity of sink.