The utility model relates to the technical field of hand-cranking power generation body builders, and discloses a magnetic resistance power generation hand-cranking body builder which comprises a shell, a body building mechanism is arranged in the shell, and the body building mechanism comprises a power generation part. According to the magnetic resistance power generation hand-cranking body builder, by arranging a first rotating shaft, a
bevel gear, a second rotating shaft, a generator, a fan-shaped belt wheel, a mounting rod, a belt wheel, a third rotating shaft, a second connecting rod, a cross-shaped sliding block, a screw rod, a sleeve and a mounting disc, a
rotating disc is rotated, the first rotating shaft rotates, a belt drives a center shaft of the generator to rotate, and the cross-shaped sliding block is driven to move front and back by rotating the screw rod; a second connecting rod drives a mounting rod to move, the relative position of a fan-shaped belt wheel and a mounting disc is changed, the
transmission ratio of an arc-shaped belt wheel and a belt wheel is changed, the force feedback magnitude on a
rotating disc is adjusted, and the practicability of the device is improved; and by arranging the spring, the sliding rod and the sliding block, the belt is in a tight state when the device feeds back the force on the adjusting turntable by utilizing the elastic force of the spring.