Abstract: Abstract: Linseed (Linum usitassimum L.), also known as Flaxseed, belonging to family Lineaceae, is an annual herb that is one of the oldest cultivated crops, continues to be widely grown for oil, textile, and food. Currently, Linseed is cultivated in more than 50 countries, predominantly in the Northern hemisphere. The important Linseed growing countries include Canada, China, India, Argentina, and United States. In China, Linseed, as one of five most important kinds of oil crops, of the average production is 500 thousand tons per year. Linseed oil is an excellent source of the omega-3 fatty acid alpha linolenic acid (ALA) with typical levels of 55% in the oil making it ideal for function food and nutritional supplements because they have shown beneficial physiological effects. However, the high content of ALA in flaxseed oil is highly susceptible to oxidation, leading to rapid deterioration of quality. Because ALA is sensitive to heat, oxygen, and light, Linseed is usually cold pressed. Cold presses typically recover 80 to 90% of the oil from oilseeds. To exhaust extract the oil of linseed, a solvent extraction has to be used. However, solvent extraction with petroleum distillates, such as hexane, is not allowed, due to its high temperature process. In order to obtain high quality linseed oil from cold press linseed cake, subcritical butane is used to extract linseed oil and then the quality of the oil and meal obtained is studied, compared with n-hexane extraction. The affection of factors, which includes extraction temperature, time and ratio of solvent to material effecting on oil yield, is investigated, and the extraction parameters are optimized by D-optimum response surface methodology. The model equation for predicting the optimum response values is established by Design Expert software. The adequacy of the model equation for predicting the optimum response values was effectively verified by the validation. The experiment result indicates that affection of ratio of solvent to material and extraction time on oil yield are more significant than extraction temperature. The interaction between extraction temperature and ratio of solvent to material has a significant affection on oil yield. The optimum operation parameters of subcritical butane extraction are: extraction temperature 26℃，ratio of solvent to material 8.4 mL/g, and extraction time 40 min. In this optimal condition, the oil yield is 96.50% and is similar to the 96.82% predicted as maximum oil yield by the mathematical model under the condition of temperature 25.77℃ and ratio of solvent to material 8.36 mL/g with extraction time 40 min. The subcritical butane extraction of linseed oil from cold press linseed cake has a nice color and better acid and peroxide value compared to n-hexane extraction. The phospholipid content of oil extracted with subcritical butane is 0.67 mg/g, which is about 1/10 of the n-hexane extraction, and the vitamin E content are 43.78 mg/100 g, which is a little larger than the n-hexane extraction process. The linseed meal obtained from cold press linseed cake with subcritical butane extraction, which has a superior quality compared to the meal obtained by n-hexane extraction, has lower content of neutral detergent fiber and high protein solubility. These experimental results offer a good reference value for high quality processing and utilization of linseed.