The invention discloses an oscillating water column wave energy utilization gas injection artificial upwelling device with a floating breakwater function and a method and belong s to the field of marine engineering. The oscillating water column wave energy utilization gas injection artificial upwelling device with the floating breakwater function is characterized by being composed of a wave energy conversion module, a gas injection module, an anchor chain and a sinker; the wave energy conversion module is suspended on the sea surface, and the lower end of the wave energy conversion module is connected with the sinker by the anchor chain; and the upper part of the gas injection module is connected to the wave energy conversion module, and the lower part of the gas injection module is constrained by a tightening device so as to be attached on a backwave side anchor chain. The method for realizing the oscillating water column wave energy utilization gas injection artificial upwelling device with the floating breakwater function comprises the following steps: device mounting, a process of converting wave energy into air kinetic energy, a process of supplementing air into an air chamber, a process of generating artificial upwelling by gas injection, circulating and repeating. The wave energy is converted and utilized by using a back-bent-tube oscillating water column technology, the artificial upwelling is formed by a gas injection artificial upwelling technology, the device has the advantages of high wave conversion rate, obvious deep-layer seawater lifting effect, durability, good reliability, low engineering investment cost, energy saving, environment friendliness and the like and can be concurrently used as a floating breakwater.