The invention discloses an impurity-removal automatic feeding device for a carding machine. The device includes an outer box, an inner box, supporting legs, a motor, a stirring shaft, a feeding port,a discharging port, a sliding baffle plate, a spring, a heating wire, an air distribution plate, an induced draft fan and a drying box, wherein the bottom of the outer box is provided with multiple supporting legs, the inner box is located inside the outer box, bottom plates of the inner and outer boxes are overlapped, the motor is arranged on the left side of the outer box, a rotating shaft of the motor penetrates through the outer box and is connected with a driving wheel, the stirring shaft is arranged inside the inner box, a left end of the stirring shaft penetrates through the inner box,the stirring shaft is connected with a driven wheel, the driven wheel and a driving wheel are engaged with each other, the inner box is further provided with the feeding port penetrating through the top of the outer box, the discharging port is arranged below the inner box, the sliding baffle plate is arranged at the discharging port, the spring is arranged between a right end of the sliding baffle plate and the outer box, the air distribution plate is further disposed above the inner box inside the outer box, the air distribution plate is provided with the heating wire, and an air inlet pipeis arranged at a top plate of the outer box above the heating wire.