Abstract: A blade structure of an axial fan is disclosed. The blade structure includes a hub and a plural of fan blades. The fan blades are disposed equidistantly on a periphery of the hub along a rotating direction of the hub. Each fan blade includes a first blade and a second blade. The first blade has a first leading edge and a first trailing edge, and the second blade having a second leading edge and a second trailing edge. A line connecting the first leading edge and the first trailing edge of each fan blade is a first chord line. The second leading edge is located at a line extended along the first chord line, and the separation between the first blade and the second blade is smaller than a distance of adjacent fan blades on the periphery of the hub.