The utility model provides a heat exchanger, include: casing, casing have the heat transfer chamber, baffling board group, the setting of baffling board group includes first baffling board and secondbaffling board in heat transfer intracavity, baffling board group, first baffling board separates the setting with second baffling inter -plate, wherein, forms the edge between the inner wall of firstbaffling board and casing and overflows the passageway, has seted up the through -hole on the second baffling board and has overflowed the passageway in order to form central authorities. The utilitymodel provides a heat exchanger's among the prior art the problem that life is short and heat exchange efficiency is low.