The utility model provides a device for leaching black copper slag and relates to a device capable of performing gas, liquid and solid three-phase efficient reaction by adopting air microbubbles for oxygen supply and combining with mechanical mixing. The device is characterized in that an air distribution device of the device structurally comprises an air distribution main pipe, and air distribution pipes; wherein the main pipe is a horizontal pipe horizontally arranged at the inner lower bottom of a reaction tank body; one end of the horizontal pipe is closed; a flange opening is formed in the other end of the horizontal pipe; a plurality of through holes are uniformly formed in the side wall of the air distribution main pipe in the horizontal direction; the air distribution pipes are a plurality of rack pipes which are horizontally arranged at the inner lower bottom of the reaction tank body and perpendicular to the air distribution main pipe; one end of each air distribution pipe is fixedly connected with corresponding through hole formed in the side wall of the air distribution pipe; the other end of each air distribution pipe is closed; air outlets are formed in the pipe surfaces of the air distribution pipes. The device for leaching black copper slag, provided by the utility model, can enable air to be dissolved in the liquid phase in the form of microbubbles to the maximum degree to participate in the leaching and dissolution reaction, so that sufficient oxygen is supplied to the reaction, the reaction speed is high, the utilization ratios of gas and heat are high, the operation cost is low, the structure is simple, and the manufacturing is convenient.