Iron is an essential mineral found in every cell of the human body to make the oxygen-carrying proteins hemoglobin and myoglobin. More than 2 billion people face Fe deficiency. Rice can be a potentially valuable source to supplement that mineral since it is staple food for two-thirds of the world’s population. To bring the nutritional level of the milled product up to that of the whole grain (brown), rice should be enriched with thiamin, niacin and iron. Thus we searched a possible allelic source from Heuristic or core rice set, which is derived from a total 24,368 rice germplasms, to increase the mineral content in rice varieties. The concentration and distribution of Fe in 137 accessions of core set of brown rice grain flour sample were determined by ICP-OES. The range of the concentration and distribution of Fe in 137 core accessions of brown rice grain were wide, from 0.088mg/L to 1.205mg/L, with mean 0.292mg/L. To examine Fe related genes, whole-genome resequencing data of 137 accessions of rice core set were analyzed by Genome Wide Associations Study (GWAS). Our result suggests that Fe determined by ICP-OES facilitates the evaluation of the differences in Fe composition for future rice breeding program