The invention discloses a square box type floating breakwater with an oscillating water column type wave energy power generation device. A wave water inlet is formed in the ahead sea face of the square box type floating breakwater, a generating set is arranged in an airflow channel, waves enter an air chamber from the water inlet of the ahead sea face of the square box type floating breakwater, and a water column which oscillates up and down is formed; the water column oscillates up and down to force air in the air chamber to be compressed and expanded, the air passes through the airflow channel on the top of the air chamber in a reciprocated manner, the generating set is pushed to generate power, through a transmission device, the electric quantity is stored in an energy storage device for standby application, and the breakwater has the advantages of being simple and stable in structure, low in building cost, high in power generation conversion efficiency, convenient to maintain, highin adaptation and the like and can be arranged on the coast, nearshore or offshore sea area, the ocean space is effectively used, the wave energy is converted into electric energy while the wave influence is reduced, and the stable water area environment is provided for the surrounding sea area, and the ocean wave resources are reasonably used.