The present invention relates to a method for producing tantalum powder for capacitors by reducing tantalum oxide with an alkaline earth metal. The method comprises the steps of: (1) mixing tantalum oxide with an excessive alkaline earth metal reducing agent, simultaneously mixing at least one alkali metal and/or alkaline earth metal halide accounting for 10-200% of the weight of the tantalum oxide, heating the obtained mixture to a temperature of 700-1200°C in a heating furnace filled with an inert gas, and soaking for 1-10 h, so that the tantalum oxide and the reducing agent are subjected to a sufficient reduction reaction; (2) at the end of soaking, lowering the temperature to 600-800°C, vacuumizing the interior of the heating furnace to 10 Pa or less, soaking under the negative pressure for 1-10 h, so that the excessive magnesium and the tantalum powder mixture are separated; (3) thereafter, raising the temperature of the heating furnace to 750-1200°C, preferably 900-1050°C, in the presence of an inert gas, and soaking for 1-6 h, so that the tantalum powder is further sintered in the molten salt; (4) then cooling to room temperature and passivating to obtain a mixed material containing halide and tantalum powder; (5) separating the tantalum powder from the resulting mixture.