The invention discloses novel application of a human YTHDF1 (Youth-Tech-Health Domain Family Member 1) gene, that is, a human YTHDF1 gene expression amount detection reagent is applied to preparationof lung cancer clinical diagnosis reagents, a human YTHDF1 gene is applied to preparation of lung cancer medicines, compared with normal pulmonary epithelial cells, the YTHDF1 gene is highly expressed in lung cancer cells, RNA (Ribonucleic Acid) designed according to the YTHDF1 gene is capable of interfering slow viruses, inhibiting expression of YTHDF1, remarkably inhibiting proliferation of thelung cancer cells, retarding tumor cell division at a G0 / G1 phase and promoting cell apoptosis, inhibiting formation of nude mouse transplanted tumour, and furthermore the purpose of treating lung cancer can be achieved; YTHDF1 gene knockout mouse tumor formation capability detection shows that cell proliferation is remarkably inhibited, and cell apoptosis is remarkably increased; the results show that the YTHDF1 gene can be used as a target for lung cancer treatment, and wide prospects are provided for development of lung cancer treatment medicines based on YTHDF1 genes in future.