A heat exchanger, comprising a heat exchange core, the heat exchange core comprising a plurality of first plates, a plurality of second plates and fins, wherein the first plate comprises a first plate surface, a plurality of protrusions protruding from the first plate surface, and a second plate surface opposite to the first plate surface, the second plate comprises a first plate surface and a second plate surface opposite to the first plate surface, a first fluid passage and a second fluid passage isolated from each other are formed in the heat exchange core, the fin is arranged between the second plate surface of the first plate and the first plate surface of the second plate, and the protrusions are located between the first plate surface of the first plate and the second plate surface of the adjacent second plate, a first passage is formed between the second plate surface of the first plate and the first plate surface of the second plate, the first passage is part of the first fluid passage, a second passage is formed between the first plate surface of the first plate and the second plate surface of the second plate, and the second passage is part of the second fluid passage, the first plate further comprises a first corner hole portion and a second corner hole portion recessed into the first plate surface, a third corner hole portion and a fourth corner hole portion protruding from the first plate surface, and a first recess and a second recess recessed into the first plate surface, protruding structures corresponding to the first recess and the second recess of the first plate are provided on a second plate surface side of the first plate, the first recess of the first plate is connected with the second recess, characterized in that two end portions of the first recess of the first plate are wider than a middle portion of the first recess, and the two end portions of the first recess of the first plate are wider than the second recess. the first plate comprises a first plate surface, a plurality of protrusions protruding from the first plate surface, and a second plate surface opposite to the first plate surface, the second plate comprises a first plate surface and a second plate surface opposite to the first plate surface, a first fluid passage and a second fluid passage isolated from each other are formed in the heat exchange core, the fin is arranged between the second plate surface of the first plate and the first plate surface of the second plate, and the protrusions are located between the first plate surface of the first plate and the second plate surface of the adjacent second plate, a first passage is formed between the second plate surface of the first plate and the first plate surface of the second plate, the first passage is part of the first fluid passage, a second passage is formed between the first plate surface of the first plate and the second plate surface of the second plate, and the second passage is part of the second fluid passage, the first plate further comprises a first corner hole portion and a second corner hole portion recessed into the first plate surface, a third corner hole portion and a fourth corner hole portion protruding from the first plate surface, and a first recess and a second recess recessed into the first plate surface, protruding structures corresponding to the first recess and the second recess of the first plate are provided on a second plate surface side of the first plate, the first recess of the first plate is connected with the second recess, characterized in that two end portions of the first recess of the first plate are wider than a middle portion of the first recess, and the two end portions of the first recess of the first plate are wider than the second recess.