The utility model discloses a milk mixing machine and a mixer thereof. The mixer comprises a cup body (4), an annular upper cover (7) and a water spraying passage (3), wherein the cup body (4) is provided with a mixing cavity and an outlet pipe (5) which is communicated with the mixing cavity; the annular upper cover (7) is arranged along an opening of the cup body (4), and a water cavity (2) which is arranged along the circumferential direction of the cup body (4) is formed between the annular upper cover (7) and the cup body (4); the water spraying passage (3) is communicated with the water cavity (2) and used for spraying water flow into the mixing cavity, and the water spraying passage (3) is arranged to form an angle with the inner wall of them mixing cavity. By adopting the mixer, the mixing uniformity of the milk powder and water can be effectively improved.