The utility model discloses a catalyst mixing device for treating wastewater containing heavy metal ions. The utility model belongs to the field of wastewater treatment, the utility model discloses acatalyst mixing device for treating wastewater containing heavy metal ions. Catalyst mixing cartridge, a plurality of water inlet holes are formed in the outer end of the catalyst mixing cylinder; a plurality of water inlet holes are uniformly distributed in the outer end of the catalyst mixing cylinder; a rotary through hole is formed in the upper end of the catalyst mixing cylinder; a material guide opening is dug in the upper end of the catalyst mixing cylinder; the rotary through hole is communicated with the material guide opening; a threaded rod is slidably connected into the rotary through hole; stirring blocks are fixedly connected to the lower ends of the threaded rods; the upper end of the threaded rod is fixedly connected with a limiting rod; a connecting plate is fixedly connected to the outer end of the limiting rod, a sliding hole is dug in the outer end of the connecting plate, an auxiliary rotating rod is slidably connected into the sliding hole, and a hard rubber pad is fixedly connected to the upper end of the auxiliary rotating rod, so that various catalysts can be uniformly mixed and stirred, and meanwhile, waste of the catalysts in the using process can be reduced.