Disclosed is a section structure of a motorcycle tire. The tire includes a tread part, sidewall parts, and bead parts. Each sidewall part is composed of an upper circle line and a lower straight line, wherein an obtuse angle is formed between the circle line and the straight line. Toothed lines are arranged on the straight lines in a full circumferential manner, and rounding is arranged between the sidewall parts and the bead parts. Circle lines and straight lines form the sidewall parts and make the sidewall parts be broken lines. Rigidity of the sidewall parts is ensured, so that the tire can well engage with a rim, and bead parts are protected from being separated from the rim. Further, toothed line design is added at straight lines of the sidewall parts, thereby reducing the weight of the whole tire. Rounding is arranged between the sidewall parts and the bead parts, so that stress concentration is prevented from generation between the sidewall parts and bead parts, and the strength of the bead parts is ensured. When the tire travels in a state of lower inner pressure, the tire can buckle the rim, and gas retention of the tire is improved for getting to the nearest maintenance point.