Research on the quality characters of quinoa seed could be useful in quinoa breeding, processing, and consumption. The quality characters of 4 domestic and 56 overseas quinoa accessions were analyzed. The results showed that the average contents of thousand seed weight, ash, protein, starch, fat, crude fiber, total flavones, and total polyphenols in 60 quinoa accessions were 4.23 g, 2.28%, 14.03%, 57.71%, 6.53%, 2.46%, 1.83 mg/g, and 1.49 mg/g, respectively. Domestic quinoa accessions had higher content of ash 3.47%, protein 14.92%, and total polyphenols 1.78 mg/g. Peruvian quinoa accessions had higher content of fat 6.69%, crude fiber 2.66%, and total flavones 2.03 mg/g. American quinoa accessions had higher content of starch 59.91%. Bolivian quinoa accessions had higher content of thousand seed weight 4.32 g. Quinoa with different seed colors showed different quality. Black quinoa had higher content of protein, white and red quinoa had higher content of starch, and red and black quinoa had higher content of crude fiber, total flavones, and total polyphenols.