Seed proteins, starch proteins and granule-bound starch synthase (GBSS) proteins were extracted and purified from buckwheat seeds. By using SDS-PAGE and EITB analytical methods, the protein was extracted from seeds of non-waxy sorghum as a check. The results showed that there existed one clearly and densely colored band with molecular weight of 60 KD in eight of common buckwheat cultivars. It was also noticed that there existed a high degree of homology of the 60 KD protein between sorghum and buckwheat. The GBSS protein extracted from buckwheat seeds could be clearly recognizable by the electrophoretical analysis of antiserum (produced by the endosperm starch bounded protein of sorghum as an antigen) by EITB method. It suggested that GBSS protein presented in buckwheat seeds.