The invention discloses a one-way automatic-discharging hopper wagon which comprises a wagon body, wherein the bottom surface of the wagon body is provided with a bottom door and a bottom door opening and closing mechanism for controlling the opening and closing of the bottom door; at least one transverse hopper is distributed in the lower bottom of the wagon body; each hopper is sealed by the bottom door; the bottom door opening and closing mechanism is in transmission connection with the bottom door and is matched with a ground collision device. The bottom door is automatically opened and closed while the wagon moves in a positive direction. The hopper wagon provided by the invention is capable of automatically opening and closing the bottom door under the effect of mechanical power with no need of a wagon wind source, and is energy-saving and environment-friendly; a door opening lever and a door closing lever are respectively positioned at two ends of a transmission shaft; the bottom door opening and closing mechanism is simple in structure, light in dead weight, convenient to overhaul and high in discharging efficiency. All walls of the wagon body are of a straight wallboard beam structure, and end walls are obliquely arranged and can be matched with the hoppers, so that hopper wagon can discharge completely, conveniently and rapidly; a brake device, a wagon hook buffering device and a steering bogie device are distributed at the inclined lower parts of the end walls, so that the conveying space can be effectively utilized and the wagon body strength is enhanced.