The invention discloses spherical tantalum powder and a preparation method and application thereof, and relates to the field of metal powder preparation. The preparation method comprises the steps of raw material weighing, briquette preparation, tantalum strip sintering, primary electron beam smelting, secondary electron beam smelting, hydrogenation, tantalum ingot smashing, dehydrogenation, hydraulic classification, drying, heating treatment and mixing, an oxygen content of the prepared spherical tantalum powder is smaller than or equal to 150 ppm, a carbon content is less than or equal to 20 ppm, an iron content is less than or equal to 10 ppm, and the electrical property is that a working voltage of a liquid tantalum capacitor is 75-150 V; a specific capacitance CV of an anode of the capacitor is 2000-4000 [mu] FV/g; and a leakage current is less than or equal to 4.5 * 10 <-4 > [mu] A/[mu] FV, and a breakdown voltage is greater than or equal to 350 V. The tantalum powder has proper particles and pore size distribution and impregnation characteristics, a conductive polymer can enter the anode more easily, more charges are led out, and the capacitance of the anode is higher. And meanwhile, in the anode forming process, an oxidation film grows more uniformly, the leakage current is smaller, and the breakdown voltage is higher.