Provided is a controllable and adjustable slag discharging bin door of a TBM. The bin door comprises a discharging hopper slag discharging bin door body of which one end is fixedly connected to a front shield body. The slag discharging bin door body is formed by a left side movable bin door and a right side movable bin door. One end of a flashboard of the left side movable bin door and one end of a flashboard of the right side movable bin door are movably hinged to the other end of a slag discharging hopper. The lower parts of the bin door flashboards are connected with an oil cylinder via pin holes. The oil cylinder is connected to a solenoid valve of a hydraulic system via an oil pipe. The solenoid valve is used for controlling the oil cylinder to stretch and be retracted. According to the utility model, the original fixed slag discharging bin door is changed into the controllable and adjustable slag discharging bind door, size of an opening of the slag discharging bin door can be adjusted and controlled and slag discharging quantity can be controlled via the hydraulic control system; earth pressure is established in front of a knife disc, so a limited pressure maintaining function is achieved, thereby minimizing or reducing effects on tunneling construction of the TBM in unfavorable geological conditions and increasing efficiency and safety of TBM construction; and the bin door is simple in structure and convenient to use, and adjustable range of the left and right side bin doors is from 0 DEG to 90 DEG.