The invention discloses a gas-liquid-solid three-phase abrasive flow plane polishing system based on a cavitation effect, comprising a two-degree-of-freedom moving device, a gas-liquid-solid mixing device, a rotary driving device, a cavitation polishing tool, a workpiece clamping device, a workpiece processing pool, an abrasive flow circulation device, a high-pressure gas injection device and a console, wherein the cavitation polishing tool comprises an outer constraint block and an inner constraint block which jointly form an annular narrow-slit flow channel with a large inlet and a small outlet; and the annular narrow-slit flow channel communicates with a through hole in a rotary spindle through an internal flow channel in an outer constraint body. The gas-liquid-solid three-phase abrasive flow plane polishing system based on a cavitation effect uses the principle of structural cavitation to set the annular narrow-slit flow channel on a cavitation polishing tool, and realizes the structural cavitation of the liquid by using a flow channel design with a larger inlet and a smaller outlet, and realizes the high-efficient material removal rate of the workpiece surface; and the liquidsecondary cavitation is realized by the design of a round corner on the cavitation polishing tool, so that the efficiency of fluid polishing is improved.