Real-time PCR and Western blot were used to detect the expression changes of EMT-related markers, E-cadherin and Vimentin, in A549 lung cancer cells treated with nicotine; The transposition of β-catenin protein expression was determined by immunofluorescence; Scratch test and Transwell invasion assay were used to detect the effects of nicotine on lung cancer cell migration and invasion. The gene discussed is CDH1; the disease is lung cancer.