The invention discloses a municipal sewage treatment device and a using method thereof, and relates to the field of environmental protection. The device is characterized in that the device includes areaction tank, one side of the upper part of the reaction tank is connected with a water inlet tube, one side of the lower part of the reaction tank is connected with a water outlet tube, the water inlet tube is connected with a water inlet pump, the water outlet tube is connected with a water outlet pump, the bottom of the reaction tank is tapered, and is connected with a filter press through a sludge discharging tube, the middle part of the sludge discharging tube is connected with a sludge discharging pump, the water outlet of the filter press is connected with the reaction tank through a return tube, the middle part of the return tube is connected with a return pump, a stirrer is fixedly connected in the reaction tank by a fixed rack, a feeder is arranged at the upper side of the innerwall of the reaction tank, and the feeder is filled with a heavy metal capturing agent. Sewage is treated by the heavy metal capturing agent, and heavy metal ions are combined in a chelation manner,so the treatment effect on heavy metals is greatly improved, and the treated sewage does not contain heavy metals or contains a very small amount of heavy metals, and is harmless to the environment.