A method for preparing a high purity tantalum powder, comprising the following steps in turn: 1) Subjecting a high purity tantalum ingot to a hydrogenation treatment, wherein the high purity tantalum ingot refers to tantalum ingot having a tantalum content of more than 99.995%; 2) Crushing and sieving the tantalum scraps as prepared after the hydrogenation of the tantalum ingot to tantalum powder, and then purifying the powder by pickling to remove impurity contaminations introduced during crushing, wherein the tantalum scraps are crushed to a level that the resultant powder is of a size of 20 μm to 37 μm (can pass through 400- to 700-mesh sieves); 3) Subjecting the tantalum powder obtained in the step 2) to a high-temperature dehydrogenation treatment, wherein the high-temperature dehydrogenation is carried out as follows: tantalum powder is heated at 800-1000 °C and the temperature is kept for 60-300 minutes; following this, the tantalum powder is subjected to cooling, discharging, and sieving to give dehydrogenated tantalum powder; 4) Subjecting the tantalum powder obtained in the step 3) to a deoxygenation treatment, wherein the deoxygenation temperature is lower than the dehydrogenation temperature by 50-300 °C and during the deoxygenation treatment the tantalum powder is mixed with 0.2-2.0% of metal magnesium powder by weight of the tantalum powder; 5) Subjecting the tantalum powder obtained in the step 4) to pickling, washing, baking to dry, and sieving; and 6) Subjecting the tantalum powder obtained in the step 5) to a low-temperature heat treatment, and then subjecting the treated tantalum powder to cooling, passivating, discharging, and sieving to give the finished product, wherein said low-temperature heat treatment is performed by keeping the temperature of 600-1200 °C for 15-90 minutes at a vacuum level of 10 -3 Pa or higher, wherein the tantalum powder has a purity of greater than 99.995%, as analyzed by a GDMS, wherein the tantalum powder has an oxygen content of not more than 1000 ppm, a nitrogen content of not more than 50 ppm, a hydrogen content of not more than 20 ppm, and a magnesium content of not more than 5 ppm, and wherein the tantalum powder has a particle diameter D50 < 25 μm. 1) Subjecting a high purity tantalum ingot to a hydrogenation treatment, wherein the high purity tantalum ingot refers to tantalum ingot having a tantalum content of more than 99.995%; 2) Crushing and sieving the tantalum scraps as prepared after the hydrogenation of the tantalum ingot to tantalum powder, and then purifying the powder by pickling to remove impurity contaminations introduced during crushing, wherein the tantalum scraps are crushed to a level that the resultant powder is of a size of 20 μm to 37 μm (can pass through 400- to 700-mesh sieves); 3) Subjecting the tantalum powder obtained in the step 2) to a high-temperature dehydrogenation treatment, wherein the high-temperature dehydrogenation is carried out as follows: tantalum powder is heated at 800-1000 °C and the temperature is kept for 60-300 minutes; following this, the tantalum powder is subjected to cooling, discharging, and sieving to give dehydrogenated tantalum powder; 4) Subjecting the tantalum powder obtained in the step 3) to a deoxygenation treatment, wherein the deoxygenation temperature is lower than the dehydrogenation temperature by 50-300 °C and during the deoxygenation treatment the tantalum powder is mixed with 0.2-2.0% of metal magnesium powder by weight of the tantalum powder; 5) Subjecting the tantalum powder obtained in the step 4) to pickling, washing, baking to dry, and sieving; and 6) Subjecting the tantalum powder obtained in the step 5) to a low-temperature heat treatment, and then subjecting the treated tantalum powder to cooling, passivating, discharging, and sieving to give the finished product, wherein said low-temperature heat treatment is performed by keeping the temperature of 600-1200 °C for 15-90 minutes at a vacuum level of 10 -3 Pa or higher,