The invention discloses a double-effect steam heat exchanger which comprises a preheating tank arranged on the lower portion and a heating tank arranged on the upper portion. The side face of the double-effect steam heat exchanger is provided with a steam inlet and a steam outlet. A first heating channel is arranged in the preheating tank, a second heating channel is arranged in the heating tank, one side face of the first heating channel is provided with a plurality of first heating pipes, the surface of each first heating pipe is provided with a plurality of small convex blocks, and the angle between each first heating pipe and the horizontal direction is 65-70 degrees. The side face of the second heating channel is provided with a plurality of second heating pipes in the same shape as the first heating pipes. The angle between each second heating pipe and the horizontal direction is 40-44 degrees. The joint between the preheating tank and the heating tank is provided with a two-layer horizontal tank. An upper layer of filter net and a lower layer of filter net are arranged in the two-layer horizontal tank. According to the double-effect steam heat exchanger, the structure is novel, operation is convenient, heating is carried out twice, waste gas is evenly heated, the heated area is large, the heat transfer efficiency is high, drying is fast, the temperature can be accurately controlled, the tail gas concentration is lowered, energy saving, consumption reduction and emission reduction are achieved, and practicability and environmental friendliness are quite good.