A dryer, comprising a drying drum, a drum motor driving the drying drum to rotate, and a drying fan for making dried hot air enter into the drying drum; wherein, the drying fan comprises a volute, a fan disposed in the volute, and a drying motor driving the fan to rotate; the drum motor and the drying motor share one motor, wherein the motor is capable of forward and reverse rotation, and drives the drying drum and the fan to rotate forward and reversely; the amount of air flow passed by the fan is same in both cases of forward and reverse rotation, wherein the volute of the drying fan comprises two parts which are a first case and a second case, and is formed by connecting the two parts in snap-fit pattern in an axial direction of the fan; an air inlet is arranged at the first case in the axial direction of the fan, and an air outlet is arranged at the volute in a radial direction of the fan, wherein the second case of the volute of the drying fan comprises a bottom plate, and a side plate mounted on one side of the bottom plate; wherein the side plate encloses a circular-like contour which is formed by connecting a plurality of involute contours; an opening is configured on the circular-like contour, each of two sides of the opening is outward provided with a straight plate; two straight plates are respectively tangent to the circular-like contour on both sides of the opening to form an U-shaped contour; an area between the two straight plates communicates with the opening to form the air outlet of the volute; and the fan is arranged in the circular-like contour, wherein a gap between the volute and the fan gradually increases toward the air outlet from the bottom of the U-shaped contour. a drying drum, a drum motor driving the drying drum to rotate, and a drying fan for making dried hot air enter into the drying drum; wherein, the drying fan comprises a volute, a fan disposed in the volute, and a drying motor driving the fan to rotate; the drum motor and the drying motor share one motor, wherein the motor is capable of forward and reverse rotation, and drives the drying drum and the fan to rotate forward and reversely; the amount of air flow passed by the fan is same in both cases of forward and reverse rotation, wherein the volute of the drying fan comprises two parts which are a first case and a second case, and is formed by connecting the two parts in snap-fit pattern in an axial direction of the fan; an air inlet is arranged at the first case in the axial direction of the fan, and an air outlet is arranged at the volute in a radial direction of the fan, wherein the second case of the volute of the drying fan comprises a bottom plate, and a side plate mounted on one side of the bottom plate; wherein the side plate encloses a circular-like contour which is formed by connecting a plurality of involute contours; an opening is configured on the circular-like contour, each of two sides of the opening is outward provided with a straight plate; two straight plates are respectively tangent to the circular-like contour on both sides of the opening to form an U-shaped contour; an area between the two straight plates communicates with the opening to form the air outlet of the volute; and the fan is arranged in the circular-like contour,