It is proved for the first time by means of measuring the retention values of 16 compounds that the relationship between solute retention and composition of eluent MeOH/HO in reversed phase (RP) system can be described with the equation In k’=b+bC+blnCwhich was drawn on the basis of liquid-solid chromatography (LSC) mode. The brief discussion about the several constants in the equation has been done.