Abstract: Protein content (PC) of the grain is one of the most important quality indexes of rice. Grain development on rice panicle is asynchronous. However, little is known what difference in the PC characters among the grains at different position within a rice panicle. The primary objective of this study is to elucidate the spatial distribution of protein content in rice grain with erect panicle and curved panicle. This study investigated the distribution of the percentages of PC for different grains on a panicle. The experiment with two cultivars and two nitrogen rates was conducted in Nanjing. All primary branches on a panicle were evenly divided into three parts of the upper, middle and basal. The grains were numbered as 1 to 6 on a primary branch and 1 to 3 on a secondary branch from the top to base. Results indicated that frequency of grains at different PC range in a panicle was normal distribution. The grains PC on a primary branch were greater than those on a secondary branch at the same part of a panicle; on a primary branch, the grain 2 had the least PC, and the grain 1 had the greatest; on a secondary branch, the grain 1 had the greatest PC. The distribution of PC at different parts within a rice panicle or on a primary branch or on a secondary branch varied with the cultivar and the amount of nitrogen applied. Application of nitrogen fertilizer could decrease the difference of grains PC in different position within rice panicle when the amount of nitrogen was between 110 kg/hm² and 220 kg/hm².