Exogenous Gibberellins (GAs) are applied in agriculture broadly and their physiological functions and biochemistry mechanism become more and more clear, but little is known about the effect of GAs on the reserve substance accumulation during seed maturing.In this paper, it is shown that GAs acts as a physiological regulator in the regulation of carbohydrate, protein, and lipids accumulation in developing seeds of Brassica Napus.It was found that the oil and total sugar content of seeds increased by 4.70% and 6.77%, and the crude protein content decreased by 3.18% in the samples treated with GA3 at 15 DAF (days after flower);the total sugar content increased by 4.10%, and the crude protein content decreased by 5.77% treated with GA3 at 25 DAF;the crude protein and total sugar content increased by 5.85% and 5.04% treated with GA3 at 35DAF.