The present invention relates to a pet retractor, more particularly to an emergency self-locking pet retractor, comprising a collar, a leash, a leash spool, a shell body and a grip handle, in which it also comprises an emergency self-locking device. The emergency self-locking device includes a switch sliding block disposed on an external surface of the shell body and inserted into the shell body, a self-locking sliding block and a return spring thereof disposed in the shell body and attached to the switch sliding block, a self-locking baffle and a return torsion spring thereof disposed on an external surface of the leash spool and whose one end is hinged on the leash spool, and a self-locking baffle block disposed at the corresponding part on the external surface of the leash spool. When the pet suddenly breaks out or rises up, the emergency self-locking device can automatically lock the spool to prevent the leash from being pulled out, so that the pet cannot run around, attack people or damage properties. The pet is well protected from being hit by vehicles and it cannot hurt others. Consequently, the pet's safety is ensured, other people and properties will not be hurt or damaged and the owner's economic loss is avoided.