NOVELTY - Forming fuel involves acidifying municipal sludge using inorganic acid, adjusting pH of sludge at not less than 3; adding 0.2-0.6 g/l iron salt into acidified sludge, stirring for 20-60 minutes, placing it in electrolytic cell, centrifugating, collecting solid residue, and removing heavy metals from wet sludge; agitating wet sludge in closed reactor to obtain sludge (a1); adding lime powder into sludge (a1) to form sludge (b1), adjusting pH of sludge (b1) to 6.5-7.5; mechanically dewatering sludge (b1) to obtain sludge (c1) and subjecting sludge (c1) via spiral conveyor to sludge drying machine.    USE - For the preparation of fuel from a municipal sludge (claimed).    ADVANTAGE - The use of sludge in the present fuel processing method greatly reduces utilization of heavy metals. The present method is environment-friendly; and produces fuel having calorific value of greater than or equal to 8000 KJ/Kg, which can be used as a high-quality fuel.    DETAILED DESCRIPTION - Preparation of fuel from a municipal sludge involves acidifying sludge using inorganic acid, adjusting pH of sludge at not less than 3; adding 0.2-0.6 g/l iron salt into the acidified sludge, then stirring for 20-60 minutes, placing the resulting sludge in an electrolytic cell at 15-30 V for 3-6 hours, after completion of the electrolysis, subjecting the sludge to centrifugation, collecting solid residue, and removing heavy metals from wet sludge; placing the wet sludge in closed reactor, performing radial axial agitation while stirring to obtain sludge (a1); adding 3 times lime powder into wet sludge (a1) to form sludge (b1), adjusting pH of the sludge (b1) to 6.5-7.5, where lime powder is added in an interval of 10-20 minutes; mechanically dewatering the resultant sludge (b1) to obtain sludge (c1) with water content of less than or equal to 80%; and subjecting the sludge (c1) through spiral conveyor to a sludge drying machine using heat source (preferably flue gas waste heat and waste steam), where temperature is 105-160 degrees C and drying time is 30 minutes to 2 hours, to obtain sludge (d1) with moisture content of less than or equal to 30%, where the sludge (d1) is the fuel.