The utility model provides a fixed bed device for Fischer-Tropsch synthesis to prepare liquid hydrocarbon, comprising a heater, a reactor connected with the upper part of the heater and a casing pipe which is sleeved outside the reactor and connected with the heater, wherein, a heating medium flue gas pipeline is arranged inside the heater; an inlet of the flue gas pipeline is arranged on the upper part of the heater; an outlet of the flue gas pipeline is arranged on the lower part of the heater; circulating water entering into the heater is heated through the flue gas pipeline; an inlet and an outlet for the circulating water are respectively arranged on the wall of the heater; the outlet for the circulating water is arranged on the upper part of the heater and communicated with the casing pipe outside the reactor; a feed gas pipeline is arranged inside the heater; a feed gas inlet and a feed gas outlet are arranged on the wall of the heater; the feed gas outlet is communicated with the reactor. The fixed bed device for Fischer-Tropsch synthesis can effectively solve the problem that the Fischer-Tropsch synthesis is too high in reaction heat, ensures the sufficient reaction of feed gas, and improves the conversion rate of the Fischer-Tropsch synthesis reaction.