The invention discloses a slurry bed reactor. The slurry bed reactor comprises an ascension pipe, an expansion section, a cooler, a catalyst settler and a filter. The upper portion of the ascension pipe is connected with the expansion section, part of the ascension pipe extends into the expansion section, and the part, in the expansion section, of the ascension pipe is provided with a slurry return port communicated with a reaction chamber. The bottom of the ascension pipe is connected with the cooler, and the cooler and the ascension pipe are integrated. Materials are fed into the catalyst settler in a tangent mode from the middle portion, the upper portion of the catalyst settler is provided with a barrier with a certain height so as to form a standing region, the top of the catalyst settler is connected with a gas-liquid separation chamber through a balance pipe, and the bottom of the catalyst settler is connected with the cooler. The top of the filter is connected with the gas-liquid separation chamber through a balance pipe, the bottom of the filter is connected with the cooler, and the filter is provided with a back washing device. The lower portion of the ascension pipe is provided with a liquid-phase raw material inlet and a gas-liquid raw material inlet. The reaction chamber is formed in the ascension pipe, and a liquid feed distributor and a gas feed distributor are arranged at the bottom of the reaction chamber. The hydrogenation efficiency of 14-16 g/l of hydrogenated liquid is achieved.