The invention discloses a rotary hearth furnace and method for treating lead and zinc smelting slag. The rotary hearth furnace comprises a rotatable furnace bottom, an annular hearth, a first partition, a second partition, a third partition, a first heating unit and a second heating unit. A smelting space is defined in the annular hearth, and the smelting space is divided into a feeding area, a preheating area, a decomposing area, a volatizing area, a reducing area and a discharging area in sequence according to the entering areas of materials in the circumferential direction of the annular hearth. The first partition is arranged between the feeding area and the preheating area. The second partition is arranged between the volatizing area and the reducing area. The third partition is arranged between the reducing area and the discharging area. The first heating unit is arranged in the decomposing area. The second heating unit is arranged in the reducing area. The rotary hearth furnace can solve the problem that valuable elements in lead and zinc smelting slag in the prior art cannot be comprehensively recycled, and in addition, valuable elements such as iron, lead, zinc, indium and sulfur in the lead and zinc smelting slag can be recycled in the same device.