The seed oil of flax (Linum usitatissimum L.)is notable for its high level of polyunsaturated fatty acids including linolenic acid,which could be oxidized by lipoxygenase,which result in oxidative acidity of oils.Therefore, stability and offflavors are vital characteristics that determine the quality of flax oil. Lipoxygenases (LOXs)are a class of nonheme iron containing dioxygenases which catalyze the hydroperoxidation of polyunsaturated fatty acids such as linoleic and linolenic acids. Experiments were conducted in order to elucidate the role of LOXs during seed development and in relation to seed oil quality. The full length cDNA of LuLOX1 was cloned based on flax whole genome DNA sequence database.The expression of LuLOX1 was determined by RTPCR and the catalytic activity of LuLOX1 was determined by spectrophotometer. Results have shown that the CDNA of LuLOX1gene was 2 607 bp, encoding a protein of 868 amino acids. The molecular weight and isoelectric point of LuLOX1 were 97.87 kD and 6.36, respectively.RTPCR carried out with RNAs extracted from seeds at different development stages showed that LOX is mainly expressed at early developmental stages.The results were consistent with those of LOX activity assays. The patterns of LuLOX1 expression were consistent with LuLOX1 activities.This indicated that LuLOX1 might be involved in regulation of fatty acid oxidation during seed development. These results laid the foundation for further study on the function of LuLOX1that may play an important role in enhancement of the quality of flaxseed oil through lipoxygenase.