The invention discloses a method of producing superfine cobalt powder for a hard alloy by fluidized reduction of cobalt carbonate and a production method thereof. The method comprises the following steps of: adding a cobalt carbonate raw material into a constant temperature fluidized reduction furnace, taking mixed gas of hydrogen and nitrogen as fluidized reducing gas, performing deep dehydrationafter mixing in proportion, and then introducing the mixed gas into the fluidized reduction furnace; performing fluidized reduction on cobalt carbonate for a while, then stopping heating and introducing gas, immediately introducing deeply dehydrated passivated gas into the fluidized reduction furnace, and passivating the obtained product for a while in a natural cooling process of the fluidized reduction furnace to obtain superfine cobalt powder; and filtering and separating flue gas generated in the whole reaction period to obtain soot and tail gas, returning the soot as a raw material to beused, compressing, cooling and dehydrating the tail gas and feeding the tail gas to a fuel chamber of the fluidized reduction furnace as a fuel to be used. The method disclosed by the invention has the advantages of being great in disposal capacity, short in reaction time, fine and uniform in grain size of the product, small in occupied area of the device, low in operating temperature and the like.