The APS underwater assault rifle is designed to destroy enemy personnel under water at a range of up to 30 m (depending on diving depth), provide self-defence on the ground at a range of up to 100 m, as well as protect against predators in water. Firing under water is possible from all swimmer positions as well as against surface targets from under water. The assault rifle is used to arm combat swimmers.

The APS rifle is gas-operated. Its gas chamber features a lever for changing the amount of gases to provide normal operation of the weapon both underwater and in the air. The rifle uses striker-type trigger mechanism that ensures single-shot and full-automatic fire. The mechanism operates from a return spring. A selector lever, which is also a safety catch, is located on the right side of the barrel chamber. A sight comprises fixed foresight and backsight.

The assault rifle is fed from a 26-round detachable magazine. A pull-out stock is retracted into the barrel chamber. Special coating protects the rifle in sea water.