NOVELTY - Extraction of crude heparin includes taking fresh small intestine mucous membrane, mincing, mixing with water at ratio of 1:3, adding into reaction tank, adding with salt or brine, adjusting salinity to 5.9-6.1 degrees, adding edible alkali, adjusting pH of 9-9.3, heating to 95-97 degrees C for 9-10 minutes, and collecting fish intestinal slag; filtering using 80-100 meshes filter, adding filtrate into adsorption tank, adding with clean water at volume ratio of 1:1, heating to 58-60 degrees C, adjusting salinity to 2.5-3 degrees, and adding adsorption resin at volume ratio of 0.75:100.    USE - Method for extracting crude heparin (claimed).    ADVANTAGE - The method is environment-friendly, has highest production efficiency, improves salinity to 6 degrees and product yield, and can achieve drug rate of enzymatic hydrolysis and waste residue.    DETAILED DESCRIPTION - Extraction of crude heparin comprises:    (A) taking fresh small intestine mucous membrane, mincing, mixing with water at ratio of 1:3, adding into reaction tank, adding with salt or brine, adjusting salinity to 5.9-6.1 degrees, adding edible alkali, adjusting pH of 9-9.3, heating to 95-97 degrees C for 9-10 minutes, and collecting fish intestinal slag;    (B) filtering using 80-100 meshes filter, adding filtrate into adsorption tank, adding with clean water at volume ratio of 1:1, heating to 58-60 degrees C, adjusting salinity to 2.5-3 degrees, and adding adsorption resin at volume ratio of 0.75:100;    (C) absorbing, collecting resin, and washing with clean water for 2-3 times at 40-50 degrees C to remove surface oil and impurities;    (D) draining, placing in desorption tank, adjusting salinity to 20 degrees, washing with brine at volume ratio of 2:1, stirring for 10 minutes, adjusting salinity to 17-18 degrees, adjusting pH to 8.3-8.5, heating to 55-60 degrees C, and stirring for 2-2.5 hours to obtain first desorption resin and desorption filtrate; taking first desorption resin, adjusting salinity to not less than 20 degrees, heating to 55-60 degrees C, and stirring for 2-2.5 hours to obtain second desorption resin and desorption filtrate; taking second desorption resin, filtering, soaking in brine at 20-25 degrees C, and repeating second step;    (E) recycling second desorption filtrate; adding first desorption filtrate to precipitation bucket, adjusting pH to 9-12, precipitating for more than 12 hours, separating alkali protein and other impurities, and collecting precipitate at the bottom of bucket;    (F) filtering supernatant, adding hydrochloric acid, stirring, filtering, adjusting pH of supernatant to neutral, adding 70 degrees ethanol, stirring, filtering, adding 30-35 degrees ethanol to supernatant, adjusting pH to 8-9, and precipitating for 24-48 hours to obtain supernatant and paste; and    (G) discharging supernatant, collecting paste, filtering using cotton suspended filter for 24 hours, taking out, and drying.