The “Technique of continuous extraction and converse retention” is used to separate effective ingredients from soybean. The cost of soybean concentrated protein(purity is higher than 70% )is firstly reduced to less than 2 200 yuan/ton, which is 1/3 of the cost of the same kind of food in domestic and international market. Adding 5%〜8% soybean concentrated protein to flour, the content of soybean protein of staple flour food will increase by 3.5%〜5.6%. In addition, processing quality of staple flour food will be improved While the price of flour or staple flour food remains unchanged.