The invention provides a method for preparing a tantalum billet or a tantalum alloy billet. The method comprises the following steps of a) performing compression molding on tantalum powder or tantalum alloy powder, and performing presintering on a billet which is subjected to compression molding in a vacuum sintering furnace; b) performing vacuum vertical sintering on the prepared billet to produce the tantalum billet or the tantalum alloy billet. According to the method, the tantalum billet or the tantalum alloy billet is prepared by adopting presintering and vacuum vertical sintering; the presintering in the vacuum sintering furnace is induction sintering to ensure that the uniformity of the billet after sintering is consistent; then the billet is subjected to vacuum vertical sintering; because a pre-sintering stage before vacuum vertical sintering ensures that the uniformity of the billet is relatively good, the uniformity of the billet can be ensured by performing vacuum vertical sintering on the billet, so that the performance uniformity of the billet is relatively good.