The invention discloses a use of a bufadienolide compound in preparing medicines for treating oral mucosal malignant tumors. Anti-cancer experiments of human tongue squamous cancer cells are carried out in vitro through a bufadienolide extract and monomeric compounds, namely gamabufalin, arenobufagin, telocinobufagin, bufotaline, cinobufagin, desacetylcinobufotalin, heloniogenin, resibufogenin, and cinobufotalin, and experimental results show that the bufadienolide compound has strong inhibition effect on tongue squamous cancer cells and compared with the bufadienolide extract and eight monomeric compounds, namely gamabufalin, arenobufagin, telocinobufagin, bufotaline, desacetylcinobufotalin, heloniogenin, resibufogenin, and cinobufotalin, cinobufagin has a stronger anti-tumor cell activity. The bufadienolide compound provided by the invention has clear components, controllable quality, strong anti-tumor activity and little adverse reaction and is expected to be developed into a novel anti oral mucosal malignant tumor medicine.