The invention discloses an in-wall refrigerator comprising a refrigerator body, a wall hole used for accommodating the refrigerator body, environmental temperature spaces surround the refrigerator body, and an outdoor cold-air refrigerating system. Doors of the refrigerator face indoors; the rear wall of the wall hole faces outdoors, covers the rear of the refrigerator, and is adjacent to the indoor environment; a frame-shaped isolation plate is sealed between the inner side of the wall of the wall hole and the peripheries of the doors to isolate the wall hole from the indoor environment. The invention further discloses a temperature control method of the in-wall refrigerator; energy of the refrigerator is saved through synergetic refrigeration by utilizing outdoor cold air and low temperature of the environmental temperature spaces of the in-wall refrigerator when the temperature outdoors is low, the refrigerator can be used normally when the temperature outdoors is high, and meanwhile, indoor occupation of area and space and influences on users by the magnetic field of the refrigerator can be reduced.