The invention discloses a one-way transmission structure of a main shaft. The one-way transmission structure of the main shaft comprises a snap spring, a gasket, an inputting assembly, a cylindrical end face bevel gear, an inner gear ring and the main shaft. The inputting assembly comprises an inputting driver, a straight tooth cylindrical gear, small gears, equal-height columns, rivets and a base; the small gears are fixed to the base through the equal-height columns and the rivets, and are engaged with the straight tooth cylindrical gear; and the straight tooth cylindrical gear is engaged with an inner gear ring of the inputting driver. Due to the fact that the cylindrical end face bevel gear on the main shaft is engaged with an end face bevel gear on the base of the inputting assembly,the base is driven to rotate; the small gears on the base rotate to drive the straight tooth cylindrical gear to rotate; and the straight tooth cylindrical gear drives the inputting driver to rotate.When the main shaft rotates reversely, the cylindrical end face bevel gear on the main shaft is not engaged with the end face bevel gear on the base of the inputting assembly, and transmission is nottransmitted. The one-way transmission structure of the main shaft is mainly applied to one-way transmission of continuously variable transmissions of bicycles and is compact in structure and high in transmission stability degree.