Abstract: A fan blade structure includes a case, a rotor and a fan blade unit. The case has a top portion and a sidewall portion connected to an outer periphery of the top portion to thereby define a receiving space therein. The rotor is mounted in the receiving space to contact with an inner wall surface of the sidewall portion in a tight-fit relation. The fan blade unit is formed by stamping a metal material, and includes an annular top face bearing on the top portion of the case, and a plurality of blades equally spaced along the annular top face. The annular top face defines a large-area central opening, which effectively reduces an overall weight of the fan blade unit and thereby lowers the load of the rotor and allows a fan motor in operation to reach its high limit of rotary speed and enable an upgraded fan rotating speed.