The invention discloses a self-generating exercise bike which structurally comprises an intelligent control board, a grab handle, a knob, a support, an exercise bike body, pedals, a fitness seat, a fitness seat carriage and an internal state regulation device, wherein the intelligent control board is mounted at the upper end of the support; the grab handle is locked at the upper end of the support; the support is connected with the knob; the knob is positioned at one side, which is close to the fitness seat, of the support. According to the invention, the pedals rotate to drive a motor to run,so as to implement energy saving, and on the basis of energy saving, by regulating a position of the fitness seat, different exercise modes are implemented; when the seat is fixed in the middle of the fitness seat carriage, the self-generating exercise bike can be used for conventional exercise and applicable for old people to exercise; when the seat is adjusted forwards, the seat can be risen tomake the body to change different stretching forms so as to carry out pedaling exercise; when the seat is adjusted backwards, shaking of the seat can be implemented, so that the self-generating exercise bike implements weight lose when implementing bodybuilding, and is applicable for young people to exercise.