NOVELTY - Populus euphratica leaves are processed, and calcium oxide and water are added, and extracted, and the filtrate is collected. Water is added, extracted and pump-forced-circulated, and the filtrate is collected. The two extracted filtrates are filtered, and filtrate is concentrated. Clarifying agent or adsorbent is added to filtrate, decolorization-stirred, filtered and collected. An acidic compound and aqueous ammonia are added to filtrate, concentrated, and crystallized in crystallization tank. The crystals are separated, dried and crushed, to obtain salicin product.    USE - Extraction of salicin from leaves of P.euphratica leaves (claimed).    ADVANTAGE - The method environmentally-friendly provides salicin crystals having purity of more than 65%.    DETAILED DESCRIPTION - P.euphratica leaves are processed, and calcium oxide and water are added and stirred in a decomposition container for 2-8 hours. The content of calcium oxide is 8-15 wt.% with respect to content of P.euphratica leaves. Water is added to mixture, and extracted at 30 degrees C for 1.5-5 hours, pump-forced-circulated for 10-20 minutes, and the filtrate is collected. Water is added, and extracted at 30 degrees C for 1.5-5 hours, pump-forced-circulated for 10-20 minutes, and the filtrate is collected. The two extracted filtrates are filtered, and an alkaline substance is added and pH value is adjusted to 10.0-12.5. The mixture is filtered with plate-and-frame filter, and the filtrate is collected. The filtrate is concentrated to specific gravity of 1.1. 3-8 wt.% Clarifying agent or adsorbent is added to filtrate, decolorization-stirred at 70 degrees C, filtered using plate-and-frame filter, and collected. An acidic compound is added to filtrate at room temperature, and pH is adjusted to 3-5, filtered, and filtrate is collected. The filtrate is added to aqueous ammonia or ammonia and the pH value is adjusted to 7-9, concentrated to specific gravity of 1.2, and crystallized in crystallization tank at room temperature for 72 hours. The crystals are separated, dried at 80 degrees C and crushed, to obtain salicin product.