The present disclosure relates to C-glycoside derivatives having a fused phenyl ring or pharmaceutical acceptable salts thereof, a method for preparing the same, a pharmaceutical composition comprising the same, a use thereof and a method for dual inhibition of SGLT1 and SGLT2 using the same. A novel compound of the present disclosure has a dual inhibitory activity against SGLT1 and SGLT2, thus being valuably used as a diabetes therapeutic agent.