Plant-based proteins are valuable supplements to compensate the gap between supply and demand in food or feed industry. However, they lack essential amino acids, such as lysine in cereal grains and sulfur-containing amino acids in legumes, which greatly limit their wider uses for human and animals. In this study, the contents of nutritional ingredients and antinutritional factors of Caragana korshinskii Kom. and its protein isolates were quantitatively investigated. It was shown that the crude protein contents of C. korshinskii Kom. and its protein isolates obtained by alkaline extraction method (Al-CPI) and acetone precipitation method (A-CPI) were 9.1%, 50.1% and 42.6%, respectively. Amino acid contents for C. korshinskii Kom., Al-CPI and A-CPI basically exceeded FAO/WHO (2007) reference pattern for adult except sulfur-containing amino acids. The lysine in C. korshinskii Kom., Al-CPI and A-CPI were 4.1, 3.1 and 3.8 mg/100 mg crude protein respectively, which were higher than some other kind of cereal grains. The methionine in A-CPI (1.39 mg/100 mg crude protein) was even higher than that in soybean. The antinutritional factors in C. korshinskii Kom. and Al-CPI were generally lower than those in some other kind of legumes except total phenol and tannin. Total phenol and tannins in Al-CPI were 19.02 and 5.66 mg/g dry substance, respectively, but they were undetectable in A-CPI. Our study provided a detailed analysis on nutritional and antinutritional factors in C. korshinskii Kom. and its protein isolates, indicating that they have a great potential on food and feed additives.