Abstract：Brassica napus is an important oil crop. In order to improve fatty acid components in rape seed and enhance its economic value, this study analyzed the synthesis and accumulation mode of fatty acid in seed developmental stages and the expression pattern of BnFAD2, Bn FAD3 and BnFATB genes. Both of results suggest that BnFAD2, BnFAD3 and BnFATB genes play important roles in the synthesis and accumulation of oleic acid in mid-late period of seed development stage (day after pollination of 25) with its efficient expression. Through Napin promoter induction, BnFAD2, BnFAD3 and BnFATB genes were suppressed by RNA interference technology to enhance the oleic acid content. The results show that the BnFAD2, BnFAD3 and BnFATB genes expression was strongly inhibited in transgenic oilseed and the oleic acid content increased from 66.7 % to 82.9 %. At the same time, the expression of related genes upregulate synchronously.