The invention relates to the field of biotechnology, in particular to application of acetylcholin esterase, butyrylcholine esterase or mutants thereof to preparation or screening of a drug for tumor treatment. The invention provides application of acetylcholin esterase, butyrylcholine esterase or mutants thereof to preparation or screening of the drug for tumor treatment. The drug for tumor treatment is an orally taken drug. By orally taking acetylcholin esterase plasmids and butyrylcholine esterase plasmids, acetylcholin esterase and butyrylcholine esterase genes are expressed while being free outside animal chromosomes, so as to improve safety and convenience and generate better tumor prevention and treatment effects. In vitro cell and in vivo animal experiments prove that expression of acetylcholin esterase and butyrylcholine esterase has a suppression effect on non-small cell lung cancer, gastric cancer, liver cancer, breast cancer, colorectal cancer, prostatic cancer, brain glioma, head and neck cancer, blood tumor and other tumor cell strains.