The invention discloses a self-power-generation type breakwater device and a power generation method of the self-power-generation type breakwater device. The device comprises a pile foundation type semicircular breakwater, the pile foundation type semicircular breakwater comprises a semicircular arch ring and a partition plate, the opening of the semicircular arch ring is downward, and the partition plate is vertically arranged in the middle of the semicircular arch ring and equally divides the internal space of the semicircular arc ring into two inner cavities. One inner cavity is located on the land area side of the breakwater, the opening of the inner cavity is provided with a bottom plate, and a closed power generation device chamber is defined by the semicircular arch ring, the partition plate and the bottom plate. The other inner cavity is located on the head sea side of the breakwater, and it is ensured that a closed energy catching air chamber is always defined by the semicircular arch ring, the partition plate and the sea surface. An air flow channel is formed in the upper end of the partition plate, an air turbine is arranged in the air flow channel and perpendicular to the air flow direction, a power generator unit is arranged in the power generation device chamber, and the power generator unit is connected with the air turbine through a coupler. The defect that traditional hydraulic structures have a single function is overcome, the power generation device and the breakwater device are combined, and therefore the self-power-generation type breakwater device has the wave blocking and power generation functions.