The flow characteristics of an aerator inserted on the chute with a concave surface is more complex than that of on the straight chute. The area of the air intake of the aerator is a very important factor which influences the cavity size of jet flow after the aerator, the air pressure in the cavity and air concentrations in high-speed flows along the chute. The present project focused on the air intake of an aerator inserted on a model chute with a concave surface. How the area of the air intake of the aerator and the radius of chute arc affect flow characteristics are investigated. The air pressure in the cavity was indirectly derived from the jet trajectory equation. It is demonstrated that the cavity length increases with, and the air pressure in it decreases with the increasing of the air intake area at first, and then it remains unchangeable for a discharge even though the air intake area continues to increase.