Abstract: ObjectiveIn order to develop Oncorhynchus mykiss egg processing products, the nutrient components of O. mykiss eggs were evaluated. MethodThe general nutrient compositions, amino acids, fatty acids, mineral elements and vitamins of mature eggs of O. mykiss that cultured in spring water were evaluated , and nutrient quality of the eggs was also studied. ResultThe results displayed that the contents of crude protein and crude fat in fresh eggs of O. mykiss were 25.4%and 3.6%respectively. The content of total amino acids was 24.32%, including eight essential amino acids and ten nonessential amino acids. The amounts of essential amino acids was 10.79%, which accounted for 44.37%of total amino acids. The ratio of total amounts of essential amino acids to nonessential amino acids(移EAA/移NEAA) was 79.75%. Glu-tamic acid had the highest content (3.00%) in all amino acids. The amino acid scores of all essential amino acids except tryptophan were higher than the standard released by Food and Agriculture Organization of the United Nations/World Health Organization(FAO/WHO) and the first limiting amino acid was tryptophan. Three saturated fatty acids and thirteen unsaturated fatty acids were detected in mature eggs of O. mykiss, and the amount of unsaturated fatty acids was accounting for 84.40%of that of the total fatty acids. Major mineral elements(Na, K, Mg, P and Ca), trace mineral elements(Cu, Zn, Fe, Mn and Se) and vitamins(VE, VA, VB1 and VB2) were detected in the eggs. ConclusionThe eggs of O. mykiss are of great quality with high protein, low fat and comprehensive nutrition components. Thus it has great potential to be developed as heathy food.