The present invention discloses a α-(3,5-dimethoxybenzylidene)-α′-hydrocarbyl methylene cyclic ketone with the following formula: wherein R is aryl or alkyl, its preparation method is: the cyclic ketone blended with morpholine are subjected to azeotropic dehydration to give enamine, the enamine is condensed with 3,5-dimethoxybenzaldehyde and then condensed with alkyl or aryl formaldehyde under acidic or basic conditions to give the product, the present invention further discloses an antitumor agent comprising α-(3,5-dimethoxybenzylidene)-α′-hydrocarbyl methylene cyclic ketone or medically acceptable salts and pharmaceutically acceptable carriers thereof. Through the above, the present invention providesα-(3,5-dimethoxybenzylidene)-α′-hydrocarbyl methylene cyclic ketone and preparation method thereof, the said compound is a high activity antitumor agent obtained by piecing and modifying the formulas of natural anti-tumor active ingredient resveratrol and curcumin, which has a good inhibitory effect on epidermal growth factor receptor.