A blade structure of a paddlewheel of a water aerator contains: a connector, a definition area extending from a center axis of the connector, a first blade unit and a second blade unit. The connector includes a wheel defined between the first blade unit and the second blade unit, wherein a number of the multiple first blades is equal to the multiple second blades, each first blade and each second blade are separately staggered relative to the definition area, each first blade is arranged on an included angle of each second blade, and each second blade is arranged on an included angle of each first blade. Each first blade has a first extending plate connected thereon relative to a vertical rim of the definition area, and each second blade has a second extending plate connected thereon relative to a vertical rim of the definition area.
