The invention provides a one-way self-locking device which comprises a locking clamp, an outer covering cavity, a spring, a rear cover and a connecting ring. The outer covering cavity holds the locking clamp and the spring and is fastened to the rear cover. The connecting ring is connected with the outer wall of one end of the outer covering cavity, far away from the locking clamp. The one-way self-locking device is capable of automatically and quickly locking one end of a steel strand, a rebar or a cable to allow for quick connection and disconnection of the steel strand or rebar, construction efficiency is high, the cost is low, and the one-way self-locking device has the advantages of capability of self-locking, convenience in demounting and reusability.