A pressure-reduction oxygen dissolving apparatus includes a container, at least one wave-shaped layer in the container for exchanging gases, at least one oxygen storage/exchange tank on each wave-shaped layer for exchanging gases, a water inlet at the top of the container for filling water into the container, a water outlet installed at the bottom of the container for discharging water out from the container, and a gas inlet for filling oxygen into the container. The oxygen enters into the container through the gas inlet to fill up each oxygen storage/exchange tank. After the oxygen has reached a specific pressure, water enters into the container from the water inlet and flows through chambers of the oxygen storage/exchange tank, and oxygen is dissolved in water naturally. Since the pressure increases the dissolved oxygen content significantly, the water outlet can be opened to obtain water with higher oxygen content.
