A heat exchanger, comprising a first pipe, a second pipe, a third pipe, a fourth pipe and a heat exchanger core, wherein the heat exchanger core comprises a plurality of first plates and a plurality of second plates which are alternately stacked together, the first plates and the second plates cooperate with each other to form a plurality of first flow passages and a plurality of second flow passages, the first flow passages and the second flow passages are spaced from each other, each of the first plates comprises a first orifice and a second orifice, each of the second plates comprises a first orifice and a second orifice, the first orifices of the first plates and the first orifices of the second plates are in communication with each other to form a first passage, the second orifices of the first plates and the second orifices of the second plates are in communication with each other to form a second passage, and the first passage and the second passage are in communication with each other via the first flow passages or the second flow passages to form a first fluid passage; the first passage is in communication with the first pipe, and the second passage is in communication with the second pipe; and at least one damping structure is provided in the first fluid passage, and at least a part of the first fluid passage is in communication with the first pipe or the second pipe via the damping structure, an equivalent inner diameter of the damping structure is smaller than an equivalent inner diameter of each of the first orifices (61, 71) of the first plates and the second plates or an equivalent inner diameter of each of the second orifices (62, 72) of the first plates and the second plates, or, a circulation area of the damping structure is smaller than a circulation area of each of the first orifices (61, 71) of the first plates and the second plates or a circulation area of each of the second orifices (62, 72) of the first plates and the second plates; characterized in that the heat exchanger further comprises a first side plate at an outer side of the heat exchanger core, one side of the first side plate is fixed to the first plate or the second plate, another side of the first side plate is fixedly provided with a mounting plate, the first side plate is provided with a first communicating hole in communication with the first passage, the mounting plate is provided with a first connecting hole in communication with the first communicating hole, the damping structure comprises the first communicating hole, and an equivalent inner diameter of the first communicating hole is smaller than an equivalent inner diameter of the first connecting hole hole and is also smaller than an inner diameter of each of the first orifices (61, 71) of the first plates and the second plates. the first passage is in communication with the first pipe, and the second passage is in communication with the second pipe; and at least one damping structure is provided in the first fluid passage, and at least a part of the first fluid passage is in communication with the first pipe or the second pipe via the damping structure, an equivalent inner diameter of the damping structure is smaller than an equivalent inner diameter of each of the first orifices (61, 71) of the first plates and the second plates or an equivalent inner diameter of each of the second orifices (62, 72) of the first plates and the second plates, or, a circulation area of the damping structure is smaller than a circulation area of each of the first orifices (61, 71) of the first plates and the second plates or a circulation area of each of the second orifices (62, 72) of the first plates and the second plates; characterized in that the heat exchanger further comprises a first side plate at an outer side of the heat exchanger core, one side of the first side plate is fixed to the first plate or the second plate, another side of the first side plate is fixedly provided with a mounting plate, the first side plate is provided with a first communicating hole in communication with the first passage, the mounting plate is provided with a first connecting hole in communication with the first communicating hole, the damping structure comprises the first communicating hole, and an equivalent inner diameter of the first communicating hole is smaller than an equivalent inner diameter of the first connecting hole hole and is also smaller than an inner diameter of each of the first orifices (61, 71) of the first plates and the second plates.