In order to investigate the frictional behavior of hydrodynamic lubrication of the synthetic fibers, various chain lengths of PEG fatty acid esters were prepared as lubricants. The effects of carbon atoms of fatty acid in PEG fatty acid esters, surface roughness of guide and guide diameter are presented. Melting point, viscosity and surface tension were found to gradually increase with increased carbon atoms of fatty acid in PEG fatty acid esters. The frictional coefficient increased with the increase of carbon atoms of fatty acid in PEG fatty acid esters. The frictional coefficient decreased with increasing guide surface roughness, In contrast at severe condition (i.e. guide surface roughness 0.492$mu$m), the exactly opposite phenomenon occurred, namely, frictional coefficient increased with guide surface roughness. The frictional coefficient increased with the increase of the guide diameter and the frictional speed.