The invention discloses a method for manufacturing hydrodynamic bearings, which comprises providing a filling body and arranging bossily a plurality of convex areas on the surface of the filling body, arranging the filling body on the central portion of a vacuum bearing die and filling a hollow cavity of a bearing die to form a blank body of a hydrodynamic bearing with an injection molding method, removing the filling body from the blank body of the hydrodynamic bearing through a degreasing mode, and sintering the blank body of the hydrodynamic bearing. The filling body is used by the hydrodynamic bearing, and the blank body and hydrodynamic grooves of the hydrodynamic bearing can be shaped integrally through injection molding procedures, which is beneficial to increase quantity producingproperty and stability of products, and shafts of the hydrodynamic grooves of the hydrodynamic bearing are separated mutually in intervals with non-oil leakage and good hydrodynamic effects.