The method was proposed to predict retention times in gradient elution under reversed-phase high-performance liquid chromatography (RP-HPLC) based on the plate theory using 6 retention equations.It can give good prediction result with these different retention equations of three or four-parameter when tested in the retention prediction by 16 common sulfonamides(SAs) in 18 kinds of gradient conditions.Especially, the retention equation of lnk =a + bφ + cφ2 + dφ3 can give the best result: the prediction accuracy was that mean absolute deviation (MAD) was 0.70% and mean relative deviation (MRD) was-0.07%.