The invention discloses medical applications of four buxus alkaloids compounds in the preparation of antitumor medicines. Experiment results show that the four compounds KBA01, KBA02, KBA03 and KBR18, under the condition of concentration without toxicity to wild normal mouse embryonic fibroblast cells, can selectively kill mouse tumor cells with tumor specific mutant genes p53 and Ras; accordingly, the compounds are very strong in killing activity to human colon cancer cell strains with p53 mutants, but not strong in killing activity to human wild colon cancer cell strains with p53 mutants; and as shown in a GFP (Green Fluorescence Protein) reporter vector screening system of a gene promoter, the compounds KBA02 and KBA03 can activate a promoter of a cancer suppressor gene p16. The characteristics indicate that the compounds from the four buxus plant origins have application potentials for preparing personalized treatment medicines aiming at the tumor mutant genes p53 and Ras as well as the cancer suppressor gene p16.