In order to understand relationships between grain filling and other related grain yield traits at gene level and improve grain filling characteristics in rice, this study used quantitative trait loci (QTL) mapping to research grain-filling rate from a RIL including 130 lines deriving from Milyang 46 and FJCD. This research carried in Wuyishan and Putian, Fujian Province. The results were detected 10 additive QTL in two environments, located in chromosome 1, 2, 5, 6, 7, and the contribution rate for phenotype variance were from 0.92% to 24.41%. Among them, qGR-1-4, qGR-2-1, qGR-5-9 and qGR-6-7 existed significant additive × environment interaction effects, manifesting “pleiotropic effects”. Additive effects of qGR-6-7 and qGR-6-8 accounted for 24.41% of the phenotypic variation respectively. Furthermore, additive × environment interaction effect of qGR-6-7 accounted for 9.33% of the phenotypic variation.