In order to explore the changes of main nutrients and microstructure of broad bean (Vicia faba) during the process of harvesting. The composition of reducing sugar， total sugar， protein， minerals， protein amino acid composition and the microstructure of embryo of three broad bean varieties (FD6， FD13 and FD17) at three edible stages (S1， S2 and S3) were studied using the spectrophotometer， flame atomic absorption spectrophotometer， amino acid analyzer， automatic nitrogen determination analyzer and scanning electron microscope. The results showed that the content of reducing sugar， total sugar and protein of three broad bean varieties was in the range of 1.16-2.41 g/100 g， 35.87-53.46 g/100 g and 25.44%-27.45%. K， Mg， Ca and Zn were the major mineral elements in broad bean. Moreover， the changes of different mineral elements in seed coat and embryo during the edible process were diverse. The content of total amino acid， essential amino acid and medicinal amino acid of broad bean ranged from 19.59 to 88.14， 2.90 to 28.54 and 10.58 to 61.59 g/100 g protein， respectively. When taking amino acid content as the evaluation index， the qualities of FD6 and FD17 at S3 were higher than those of S1 stage. The result of correlation analysis showed that the interaction between mineral absorption and enrichment and amino acid synthesis of broad bean embryo was different from that of seed coat. Scanning electron microscope micrographs showed that there were differences in starch granules between different varieties and different edible stages. On the whole， the seed coat and embryo of broad bean are rich in nutrients.