The invention discloses a process for removing heavy metals from sludge of sewage treatment plants. The process comprises the following steps of: adding 0.5 to 30g of elemental sulfur in each litre of sludge in a bioleaching tank, respectively inoculating 1 to 5 percent of thiobacilli and 1 to 3 percent of acidophilus moulds in the bioleaching tank, carrying out aerated bioleaching on the obtained sludge for 2 to 6 days until the pH value of the obtained sludge in the bioleaching tank is less than 2, and pumping the sludge subjected to bioleaching treatment in a plate-and-frame filter press by using a pump to carry out filter press separation so as to obtain sludge from which heavy metal is removed and sewage containing the heavy metal; adding alkali into the sludge from which heavy metalis removed to neutralize the sludge and then transporting the sludge to a sludge composting plant for composting; adding alkali into the sewage containing the heavy metal until the pH value of the sewage is about 7, then putting the sewage into an electrolytic flocculation floatation device to carry out electrolytic flocculation and self-floatation treatments on the sewage, and after the obtainedliquid supernatant reaches the standard, draining the liquid supernatant; and pumping the flocculated scum of the pollutant in water into the plate-and-frame filter press for separation to obtain corresponding filter liquor and sludge, wherein the filter liquor is drained to a waste liquor recovery tank, and the sludge is transported to a hazardous waste disposal center for treatment. The processof the invention has the advantages of shortening the lixiviation period, improving the lixiviation efficiency and the variety of lixiviated heavy metal, ensuring the stability of removing heavy metal, and saving equipment investment.