The invention discloses a device for preparing brick mixture from construction waste. The structure thereof comprises a distribution box, a discharging port, an outer shell, a motor, a timer, a numerical control box, a rotating shaft, a feeding port, a mixer main body and a driver, wherein the outer shell is of U shape with two bulged sides and concave middle part; the tail end above the inner surface is moveably connected with the lateral surface of the rotating shaft in the manner of interference fit; the section of the mixer main body is of octagon shape with equal side lengths on the two sides; the rotating shaft penetrates through the centers of the two sides of the mixer main body; the thickness of the mixer main body is 3mm-6mm; a chip-processing lateral surface is arranged at an edge of the lateral surface of a circuit board; an executor is electrically connected with a circuit breaker. The device is equipped with the timer, the distribution box is used for transferring the electric energy to the timer main body, the premixing time is set for the timer main body through the circuit board in the manner of controlling an operation panel, and after the mixing time reaches the appointed time, the circuit breaker is driven by the executor to cut off the power of the motor and the mechanical running is stopped in time, so that the burning caused by excessive mechanical running is avoided.