A body-training bicycle comprises: a seat has a long central rod; a driving portion having a treading portion, a driving wheel connected to at least one treadle, a flywheel and a driving belt; the rotation of the flywheel will make the power generator generating power; an electric control portion having a control panel, a battery unit, a magnetic resisting unit, a displacement controller, and electric wires; the battery unit serving to store power from the flywheel; the magnetic coil set being installed aside a wheel periphery of the flywheel and the central shaft of the flywheel; the magnetic cell set controller serving to control the movement of the magnetic resisting unit to move closer or away from the flywheel; electric wires being installed between the power generator and the control panel and between the power generator and the battery unit.