The invention relates to a flow dispersing aerator with rotary cut orifices, which comprises a gas distribution pipe, a rotary mixing barrel and a gas distribution mechanism, wherein a rotary cut generator is mounted in the rotary mixing barrel, and comprises a rotary cut barrel coaxial with the rotary mixing barrel, multiple clockwise rotary cut flow guiding orifices uniformly formed in the barrel wall at the top end of the rotary cut barrel, and multiple reverse rotary cut flow guiding orifices uniformly formed in the barrel wall at the bottom end of the rotary cut barrel; the clockwise rotary cut flow guiding orifices and the reverse rotary cut flow guiding orifices are arranged in a staggered manner; a gas distribution orifice in the top end of the gas distribution pipe is communicated with the bottom end of the rotary cut barrel through a connecting mechanism; the gas distribution mechanism is a flow dispersing cover; a plurality of gaps are uniformly formed in the flow dispersing cover; the flow dispersing cover is connected with the rotary mixing barrel via a fastening device. The aerator has the advantages that the great rotational flow fusion of the gas phase in the liquid phase is achieved, so that a highly rich gas-liquid contact interface can be formed; the aerator is an aeration machine which has multiple comprehensive effects and is capable of producing uniformly distributed tiny rising bubbles.