The invention discloses a method for extracting fulvic acid through low-temperature carbonization. The method comprises the following steps of 1, low temperature carbonization, decomposed coal is smashed into particles with the size not larger than 4 mm, and then placed into a closed container isolated from air, and low-temperature carbonization is performed on the condition of 500-650 DEG C for 30-40 min to collect coal tar; 2, alkaline extraction, wherein coal tar and a weak base solution are mixed, the pH of the mixed solution is adjusted to be 6.0-8.0 to obtain an alkaline extraction solution, the alkaline extraction solution is stirred for digestion for 0.5-1 h, and precipitates are removed after centrifuging is performed, and an alkaline extraction supernate is obtained; 3, acid extraction, wherein a 0.5 MHNO3 solution is used for adjusted the pH of the alkaline extraction solution to 1.0-2.0 to obtain an acid extraction solution, the acid extraction solution is stirred for digestion for 0.5-1 h, precipitates are removed after centrifuging is performed, and an acid extraction supernate is obtained; 4, freeze drying, wherein the acid extraction supernate is frozen and dried to obtain fulvic acid powder. Before alkali extraction and acid extraction, low-temperature carbonization is performed on decomposed coal, organic matter in the decomposed coal can be split to the maximum extent, and the fulvic acid extraction rate is increased; weak base is adopted for alkali extraction, and equipment corrosivity is small in the extraction process.