The invention discloses a process for extracting salicin from populus euphratica fallen leaves. The process is characterized by comprising the following steps: adding calcium oxide into populus euphratica fallen leaf shreds, and adding water for decomposing; extracting the solution twice at the temperature of 30 DEG C, collecting filtrate, and combining the filtrate; adjusting the pH value to 10.0-12.5, allowing the solution to stand, and collecting the filtrate; concentrating the filtrate, adding a clarifying agent or an adsorbent for decolorizing while stirring at the temperature of 70 DEG C, and colleting the filtrate; adjusting the pH value to 3.0-5.0 at a normal temperature, allowing the solution to stand, and collecting the filtrate; adding ammonium water or ammonia gas into the filtrate for adjusting the pH value to 7.0-9.0, concentrating the filtrate till the specific weight is 1.2, and crystalizing the filtrate at the normal temperature in a static manner for 72 hours; and separating a crystal, drying the separated crystal at 80 DEG C, and smashing the dried crystal. The process has the beneficial effects that water with low environmental pollution is taken as an extraction solvent, so that the production cost and the workshop requirement are lowered; ash is removed by adopting sulfuric acid or sulfate, and the crystal is obtained through the crystallizing step, so that the purity of a final product is increased, and can be over 65 percent in general; and natural fallen leaves of populus euphratica in autumn are taken as raw materials, so that damage to vegetation is prevented.