The invention discloses a mixed microbial agent used for removing heavy metal in industrial wastewater sludge. The mixed microbial agent has the advantages that the mixed microbial agent comprises thiobacillus thiooxidans, thiobacillus ferrooxidans, aerobic denitrifier, heavy-metal-resistant bacteria and extremely-acidophilic thiobacillus, the aerobic denitrifier is used for directly converting ammonium nitrogen into a gaseous product under an aerobic condition and has effects of promoting organic matter conversion and accelerating sludge acidification; the heavy-metal-resistant bacteria are used for increasing the heavy metal tolerance of other bacteria; the extremely-acidophilic thiobacillus is used for evidently increasing the leaching efficiency of the heavy metal in a solution under astrong acid condition and shortening the leaching time of the heavy metal. Compared with a traditional method, a method using the mixed microbial agent has the advantages that the removing effect ofthe heavy metal such as Cu, Cd, Hg, Cr and Pd in the sludge is improved evidently, and the removing efficiency is increased evidently.