The invention relates to a method for enhancing heavy metal stabilization process in the urban sludge anaerobic digestion process. Municipal sludge serves as raw materials, a special vacuum reacting furnace is adopted, sludge biochar is prepared high-temperature pyrolysis under the anoxic condition, SBC is modified through glass fiber wetting, and finally the sludge biochar of a stable structure, with high voidage and resistant to acid and alkali impact is obtained; in the sludge anaerobic digestion acid production stage, the sludge is added to a reactor according to a proper proportion, free state heavy metal in the reactor can be absorbed and captured obviously, and finally the stabilizing process of the sludge heavy metal is accelerated and enhanced. The method basically cannot generate adverse influences on a sludge anaerobic digestion reaction system, the generated biogas residue is obviously lowered in the water content, and the dewaterability is obviously improved. The method can be used for remaining sludge anaerobic digestion engineering of sewage treatment plants in cities and towns, the heavy metal stabilization process in the anaerobic digestion process is effectively enhanced, the sludge stabilization process is accelerated, and the method has great significance for lowering the risk of heavy metal environmental pollution and improving the soil health quality in the utilization process of sludge lands generated after anaerobic digestion is conducted.