Disclosed is a method for producing a heat exchanger. The heat exchanger comprises heat exchange tubes extending along a first direction and arranged along a second direction perpendicular to the first direction, and a fin. The fin is provided with fin grooves for mounting the heat exchange tubes, and each fin groove is provided with an opening on one side in a third direction perpendicular to the first direction and the second direction. The method comprises: providing a heat exchange tube preform, the heat exchange tube preform having a maximum size in a second direction; providing a fin preform, a fin groove of the fin preform having a minimum size in the second direction, and the maximum size being greater than the minimum size; inserting the heat exchange tube preform into the fin groove of the fin preform, so as to generate a predetermined contact pressure between the heat exchange tube preform and the fin preform by means of the elastic deformation of at least one of the heat exchange tube preform and the fin preform, and welding the heat exchange tube preform and the fin preform together.