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 . <EOS>