The invention relates to garbage incineration equipment, in particular to a secondary combustion chamber which comprises a horizontal combustion chamber, a plasma ignition device interface, multiple guide blades, first and second grading air interfaces and a lattice wall. The horizontal combustion chamber comprises a heat-resistant knotting material inner lining and a metal outer layer, the two ends of the horizontal combustion chamber are provided with a flue gas inlet and a flue gas outlet correspondingly, the plasma ignition device interface is arranged at the flue gas inlet, and the plasmaignition device interface is provided with a primary air interface. The guide blades are in the shape of fan blades, the multiple guide blades are welded in the flue gas inlet and mounted on a central barrel of the plasma ignition device interface, and the end surfaces of the guide blades are flush with the inner surface of the heat-resistant knotting material inner lining; the first and second grading air interfaces are arranged at intervals in the axial direction of the combustion chamber and obliquely enter the combustion chamber in the circumferential direction, and an imaginary tangent circle is formed by three grading air nozzles; and the lattice wall is vertically arranged in the combustion chamber. The investment cost is low, the occupied area is small, no secondary pollutant is generated, combustible gas components and toxic substances in exhaust smoke of equipment such as a rotary kiln or a melting furnace can be effectively treated, operation is efficient, economical, safeand reliable, and adjustment is convenient.