The invention discloses a porcelain inner wall polishing device convenient for size adjustment. The porcelain inner wall polishing device comprises a first transverse plate and a first vertical plate,wherein a left side of an upper surface of the first transverse plate is fixedly connected with the first vertical plate; and a rotation device is arranged on the upper surface of the first transverse plate. According to the porcelain inner wall polishing device convenient for size adjustment, through mutual cooperation of a box, a third vertical plate, an L-shaped plate, a torsion spring, a second transverse plate and a concave plate, a porcelain can be fixed effectively, and the porcelain is prevented from being damaged due to falling in the polishing process. Through mutual cooperation ofa second motor, a fluted disc, a connecting rod, an electric push rod, polishing rods and a fourth transverse plate, the size between the polishing rods can be adjusted, thereby meeting polishing of porcelains of different sizes. Through mutual cooperation of the first transverse plate, the third transverse plate, the first vertical plate and a sleeve, the polishing device can be fixed, so that the surface of the polished porcelain is smoother.