This on-line solvent degassing equipment is installed between storage bottle and high-pressure pump of HPLC. The mobile phase solvent enters the degasser entry through permeable membrane tube placed in a vacuum region. Because of the pressure difference of the wall of the permeable membrane tube, the dissolved gas continuously leaks out of the tube thus causing degassing development of the mobile phase solvents. The degassed gas is then moved to liquid chromatography pump entrance.