A fitness bike is provided which comprises a support skeleton which comprising a triangular frame which is formed by a connection rod as a transverse rod connecting a front support leg and a rear support leg, an oblique bar of the front support leg, an oblique rod comprising a support box and a connection block of a pedaling device, and a seat column as a vertical rod; a lower end of the oblique bar is fixed on a middle of a horizontal rod of the front support leg, a rear end of the connection rod is fixed at a front side of a middle of a V-shaped rod forming the rear support leg and having an opening facing backward, and a seat support device is mounted on the top of the seat column. The structure of the fitness bike provided is simple, compact, stable, and occupies less space.