The invention discloses a height-adjustable grinding device of a coffee maker. The height-adjustable grinding device comprises a motor, a transmission part, a barrel body, a cutter disc and a height adjusting device, wherein the motor is connected with the cutter disc through the transmission part; the cutter disc is arranged below the barrel body; a powder pushing block is arranged at the outer side of the cutter disc; a plurality of blades which are horizontally arranged are arranged on the surface of the cutter disc; an empty place is arranged between the cuter disc and an inner wall of thebarrel body; a powder outlet is formed under the side of the barrel body; the height adjusting device comprises a positioning disc, supporting frames, a connection block and a limiting pin; the positioning disc is arranged above the blades; a gap is formed between the bottom surface of the positioning disc and the highest points of the blades; the outer side of the positioning disc is connected with the inner wall of the barrel body through a thread; the supporting frames are arranged at the outer side of the barrel body; one end of the connection block is connected with the supporting framesthrough the limiting pin; the other end of the connection block is connected with the positioning disc. The height-adjustable grinding device of the coffee maker, disclosed by the invention, is novelin structure, low in noises and reliable in performance; ground coffee powder is fine and uniform; the height adjusting device is arranged at the upper side of the grinding device, and the fineness of the coffee powder can be adjusted to meet the requirements of different people.