Abstract: Recombinant inbred lines (RIL, Longjian 19 × Q9086, F₈) and their parents were undertaken to study characteristics of quantitative genetics of water soluble carbohydrates (WSC) accumulation, remobilization and its contribution to grain mass in different main stem internodes at the grainfilling stage as well as the correlations among the target traits under the rainfed (DS) or wellwatered (WW) condition. All of the target traits of RIL had wide variations under both water conditions. The variation coefficient ranged from 2.7% to 62.1% under the DS, and from 1.9% to 52.1% under the WW. The diversity index varied from 0.61 to 0.90 under the DS, and from 0.64 to 0.89 under the WW. All tested traits were significantly affected by the genotype, water condition, internode and growth stage. The growth stage exerted strong impacts on the WSC content. The water condition and internode greatly influenced the WSC remobilization rate. But, the WSC contribution rate to grain was jointly controlled by the genotype, water condition and internode. There were significantly positive correlations between the WSC contents at the early flowering and grain-filling stages,  the WSC remobilization rate and its contribution rate to grain at preanthesis stage, with the higher correlation coefficients under the DS than under the WW. All traits showed low heritability under both water conditions (hB₂=0.31-0.56 under the DS, 0.44-0.67 under the WW). The numbers of gene pairs controlling all traits ranged from 6 to 29 under the DS, and from 3 to 19 under the WW. It indicated that alleles responsible for all the target traits of RIL showed substantially transgressive segregation and greatly significant sensitivity to the water condition, confirming the characteristics of quantitative traits.