The present invention relates to a substituted prop-2-en-1-one compound as shown in formula (I), and a pharmaceutically acceptable salt, polymorph, tautomer, stereoisomer, hydrate, solvate or isotopic variant thereof. Since the compound is a PPAR α and PPAR δ agonist, it can be used in a method for treating and/or preventing diseases caused by the PPAR α and/or PPAR δ, for example, in a therapeutic method of nonalcoholic steatohepatitis. Also provided in the present invention is a pharmaceutical composition comprising the compound of the present invention.