A rotary shaft structure is provided with rotational and locating functions based on a compact request condition. The rotary shaft structure includes a combination of a shaft body and a braking device, in which the braking device includes a first end provided with a limiting portion and a second end provided with an assembling portion, thereby preventing an axial displacement of a rotary shaft. The shaft body corresponding to the first end of the braking device and the limiting portion thereof includes a base portion and at least one braking portion formed on the base portion, in which a locating function is formed when an interference state of the limiting portion of the braking device and the braking portion of the shaft body is formed, thereby improving the conditions of assembly and fitting difficulties, complication and time-consuming process in conventional skills.