The invention discloses an intelligent padlock. The padlock includes a lock body and a shackle; the top of the lock body is provided with a first and second lock hole; the lock body is provided with acontrol circuit board, a stepping motor, a reduction gearbox and a mechanical transmission mechanism; the mechanical transmission mechanism includes a transmission block, a second reset spring and alock pin; the long end of the shackle is successively provided with a long strip-shaped latch clamping groove and a locking groove from bottom to top; the second lock hole is provided with a first reset spring; the bottom of the long end of the shackle is in contact with the top of the first reset spring; the side face, on the side of the second lock hole, of the lock body is provided with a latchhole; the long end of the shackle is installed in the second lock hole through a latch, the latch hole and the latch clamping groove; the control circuit board is electrically connected to the stepping motor; the stepping motor is connected to the reduction gearbox; the power output shaft of the reduction gearbox is connected to the transmission block; the transmission block drives the lock pin to insert in or rotate out of the locking groove; the second reset spring is arranged on the end, away from the locking groove, of the transmission block and fixed in the lock body; and the bottom of the lock body is provided with a USB interface. The padlock has no power supply and is not easy to damage; and the convenient changing of shackles with different lengths can be realized.