A hydrodynamic bearing structure for bearing a cooling fan, comprising: a housing having a cylindrical accommodating space, wherein an upper opening communicating with the accommodating space is provided at an upper end of the housing; a bottom plate, disposed on a bottom of the housing, wherein the bottom plate is tightly fit to the bottom of the housing, the bottom plate being an anti-friction plate; a hydrodynamic bearing, disposed in the accommodating space, wherein a rotation shaft hole extending through a top surface and a bottom surface of the hydrodynamic bearing is provided in the center of the hydrodynamic bearing; a rotation shaft, disposed in the rotation shaft hole of the hydrodynamic bearing, wherein an upper end of the rotation shaft protrudes from the top surface of the hydrodynamic bearing, and a bottom end of the rotation shaft protrudes from the bottom surface of the hydrodynamic bearing and is configured so that a contact is possible with a top surface of the bottom plate, an arc portion being provided at a bottom of the rotation shaft; and a thrust member, fixedly connected to the bottom end of the rotation shaft and accommodated between the bottom surface of the hydrodynamic bearing and the bottom plate, the thrust member being a circular plate; wherein a space in the accommodating space between the bottom surface of the hydrodynamic bearing and the top surface of the bottom plate is filled with a lubricating oil; characterized in a plurality of radially arranged guiding grooves being disposed on a bottom surface of the thrust member; a seal member tightly connected between the bottom plate and the housing being disposed at a joint between the bottom plate and the housing; a recessed portion being provided in the top surface of the bottom plate such that the arc portion can abut against the recessed portion. a housing having a cylindrical accommodating space, wherein an upper opening communicating with the accommodating space is provided at an upper end of the housing; a bottom plate, disposed on a bottom of the housing, wherein the bottom plate is tightly fit to the bottom of the housing, the bottom plate being an anti-friction plate; a hydrodynamic bearing, disposed in the accommodating space, wherein a rotation shaft hole extending through a top surface and a bottom surface of the hydrodynamic bearing is provided in the center of the hydrodynamic bearing; a rotation shaft, disposed in the rotation shaft hole of the hydrodynamic bearing, wherein an upper end of the rotation shaft protrudes from the top surface of the hydrodynamic bearing, and a bottom end of the rotation shaft protrudes from the bottom surface of the hydrodynamic bearing and is configured so that a contact is possible with a top surface of the bottom plate, an arc portion being provided at a bottom of the rotation shaft; and a thrust member, fixedly connected to the bottom end of the rotation shaft and accommodated between the bottom surface of the hydrodynamic bearing and the bottom plate, the thrust member being a circular plate; wherein a space in the accommodating space between the bottom surface of the hydrodynamic bearing and the top surface of the bottom plate is filled with a lubricating oil;