The invention discloses a slot type throttling structure for a medium inlet of a plate heat exchanger. The outside of the edge of a medium through hole on a positive heat exchange plate is eccentrically provided with a depressed area, the bottom of wider position of the depressed area is provided with at least one medium leakage injection hole, and a slow flow cavity is formed between the depressed area and a reverse heat exchange plate arranged above the depressed area; the outside of the edge of the medium through hole on the reverse heat exchange plate is concentrically provided with a convex annular zone, and the lower bottom surface of the depressed area and the upper bottom surface of the convex annular zone which are adjacent are hermetically welded; and the medium through hole on the positive heat exchange plate is slightly sunk downwards to ensure that the edge of the medium through hole of the positive heat exchange plate forms an upper convex annular zone, the medium through hole on the reverse heat exchange plate is slightly prominent upwards to ensure that the edge of the medium through hole of the reverse heat exchange plate forms a lower convex annular zone, a slot is formed between the upper convex annular zone and the lower convex annular zone which are adjacent, and the slot is communicated with the slow flow cavity. The slot type throttling structure is integratedly punch-formed at one time, has convenient manufacturing, simplifies assembly technology, and reduces production cost.