A simple and efficient method was developed for the synthesis of 4-chloro-7-methoxyquinoline-6-carnoxamide as the key intermediate of the anticancer drug Lenvatinib. Using BF3?Et2O as catalyst and solvent, the cascade formylation/addition-cyclization/chloration of 3-methoxyaniline with Vilsmeier reagent and ethyl 3,3-dimethoxypropionate at 90 ℃ for 20 min under microwave irradiation gave 4-chloro-7-methoxyquinoline-6-carboxaldehyde with 72.2% yield. After that, 4-chloro-7-methoxyquinoline-6-carboxamide was synthesized in 84.5% yield via direct oxidative amidation of 4-chloro-7-methoxyquinoline-6-carboxaldehyde with ammonium bicarbonate in the presence of CuI and TBHP under the conditions of CuI 5 mol%, reaction temperature 80 ℃ and reaction time 4 h. The procedure has the advantages of short synthetic route, cheap and easily obtained raw materials, high atomic efficiency, high yield, mild reaction condition, easy operation.