The invention discloses a multifunctional fitness device and an operation method. The device comprises a bottom plate, an outer roller carrier, an outer roller, a frame, pedals, a first synchronous wheel, a
crank, a third synchronous wheel, a second synchronous belt, a fourth synchronous wheel, a distance adjusting seat, a guide rod, a shaft, a second synchronous wheel, a second synchronous wheel hole, a lead screw, a nut, a roller seat, a roller, a connecting rod, a first synchronous belt, a pull belt, a
turbine speed
reducer, a winding drum, a winding shaft, a transmission shaft, a spring, a rotating shaft and a nut. The outer side of the bottom plate is fixedly connected with a hood, the left side of the bottom plate is fixedly connected with the frame, the middle of the frame is provided with a frame groove, the upper portion of the frame is provided with a pedal hole, the upper portion of the pedal hole is provided with a
crank hole, the middle of the pedal hole is provided with a pedal shaft, the pedal shaft penetrates through the pedal hole, the pedal shaft is rotatably connected with the pedal hole and rotates in the pedal hole, and the two sides of the pedal shaft are fixedly connected with the pedals. A first
synchronizing wheel is arranged in the middle of the frame groove.