A process for preparing tantalum powder with super-high specific capacity for capacitors by reducing tantalum oxide powder through three steps of reductions, which process comprising the steps of: a first reduction step: mixing tantalum oxide powder and a first reducing agent powder homogenously, and then carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum suboxides powder; wherein said first reducing agent is selected from the group consisting of rare earth metals, hydrides of rare earth metals and mixtures thereof; and wherein the amount of the reducing agent in the first reduction step is 0.3-0.65 times of the stoichiometric amount of reducing agent required for removing oxygen content in the tantalum oxide powder; the reaction temperature in the first reduction step is 400-1000°C, and the reaction time is 3-10 hours; a second reduction step: mixing the tantalum suboxides powder obtained from the step, in which impurities have been removed, with a second reducing agent powder homogenously, and carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum powder having high oxygen content; wherein the second reducing agent is selected from the group consisting of rare earth metals, hydrides of rare earth metals and mixtures thereof; and wherein the amount of the reducing agent in the second reduction step is 0.4-0.85 times of the stoichiometric amount of reducing agent required for removing oxygen content in tantalum suboxides; the reaction temperature in the second reduction step is 400-1000°C, and the reaction time is 3-10 hours; and a third reduction step: mixing the tantalum powder having high oxygen content obtained from the step, in which impurities have been removed, with a third reducing agent powder homogenously, and then carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum metal powder suitable for capacitors; wherein the third reducing agent is magnesium or magnesium alloy; and wherein the amount of the reducing agent in the third reduction step is 1.0-2.0 times of the stoichiometric amount of reducing agent required for removing oxygen content in tantalum powder having high oxygen content; the reaction temperature in the third reduction step is 300-900°C, and the reaction time is 2-6 hours; wherein after each reduction step, the oxidation product of reducing agent and the residual reducing agent are removed from the reaction product. a first reduction step: mixing tantalum oxide powder and a first reducing agent powder homogenously, and then carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum suboxides powder; wherein said first reducing agent is selected from the group consisting of rare earth metals, hydrides of rare earth metals and mixtures thereof; and wherein the amount of the reducing agent in the first reduction step is 0.3-0.65 times of the stoichiometric amount of reducing agent required for removing oxygen content in the tantalum oxide powder; the reaction temperature in the first reduction step is 400-1000°C, and the reaction time is 3-10 hours; a second reduction step: mixing the tantalum suboxides powder obtained from the step, in which impurities have been removed, with a second reducing agent powder homogenously, and carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum powder having high oxygen content; wherein the second reducing agent is selected from the group consisting of rare earth metals, hydrides of rare earth metals and mixtures thereof; and wherein the amount of the reducing agent in the second reduction step is 0.4-0.85 times of the stoichiometric amount of reducing agent required for removing oxygen content in tantalum suboxides; the reaction temperature in the second reduction step is 400-1000°C, and the reaction time is 3-10 hours; and a third reduction step: mixing the tantalum powder having high oxygen content obtained from the step, in which impurities have been removed, with a third reducing agent powder homogenously, and then carrying out reduction reaction in hydrogen and/or inert gas or vacuum atmosphere to obtain a tantalum metal powder suitable for capacitors; wherein the third reducing agent is magnesium or magnesium alloy; and wherein the amount of the reducing agent in the third reduction step is 1.0-2.0 times of the stoichiometric amount of reducing agent required for removing oxygen content in tantalum powder having high oxygen content; the reaction temperature in the third reduction step is 300-900°C, and the reaction time is 2-6 hours;