Abstract: A fan dynamic pressure structure having a plastic frame integrally formed around an oil-containing sintered metal powder bearing includes an oil-containing sintered metal powder bearing, a plastic frame having a middle tube integrally formed around a peripheral of a bushing body of the oil-containing sintered metal powder bearing, a blade assembly having an axial shaft penetrating through a shaft hole of the oil-containing sintered metal powder bearing, the axial shaft protruding downwardly and having an annular groove, and an annular dynamic pressure piece having an insertion hole and an annular body surrounding the insertion hole. The insertion hole is engaged with the annular groove of the fan assembly, the annular body has a plurality of curved radial dynamic pressure ditches on a surface adjacent to the oil-containing sintered metal powder bearing, of the annular body.