NOVELTY - Preparing industrial charcoal from sludge comprises: (i) sequentially adding recycled water, industrial sulfuric acid and industrial hydrogen peroxide solution into a wet sludge which is dehydrated while sewage treatment, agitating and mixing, heating the mixture and pre-treating the sludge pulp for 10-80 minutes; (ii) separating solid from liquid in the pre-treated sludge pulp and washing with water to obtain a sludge residue and filtrate; (iii) adjusting the pH value of the sludge residue to 6.5-7.5 through lime and carrying out pyrolysis in a pyrolysis tank to obtain the product.    USE - The method is useful for preparing industrial charcoal from sludge.    ADVANTAGE - The method, in comparison with the conventional process: pre-treats the wet sludge mechanically to greatly reduce the water content in the sludge and to effectively remove the heavy metals in the wet sludge; reduces the heavy metal content in the pyrolysis product; has a high calorific value of greater than or equal to 15000 kJ/kg, and thus produces industrial charcoal with high-quality; utilizes a part of the filtrate obtained in the solid and liquid separating in the pre-treatment stage; and is environmental-friendly.    DETAILED DESCRIPTION - Preparing industrial charcoal from sludge comprises: (i) sequentially adding recycled water, industrial sulfuric acid and industrial hydrogen peroxide solution into a wet sludge which is mechanically dehydrated while sewage treatment, where the volume and mass ratio of the recycled water to the wet sludge is 0.3:1-0.8:1, the volume and mass ratio of the industrial sulfuric acid (90-95 wt.%) to the wet sludge is 10:1000-15:1000 and the volume and mass ratio of the industrial hydrogen peroxide solution (30 wt.%) to the wet sludge is 20:1000-60:1000, agitating and uniformly mixing, heating the mixture to 60-95 degrees C and pre-treating the sludge pulp for 10-80 minutes; (ii) separating the solid from liquid in the pre-treated sludge pulp and washing with water to obtain a sludge residue and a filtrate, where the volume and mass ratio of the washing water to the wet sludge is 0.5:1-5:1; (iii) adjusting the pH of the sludge residue to 6.5-7.5 through lime, transferring the obtained sludge residue into a pyrolysis tank for pyrolysis, where the pyrolysis is completed to obtain the product and the water content of the pyrolysis product in the pyrolysis tank is less than or equal to 1%.