The variabilities of soil moisture, Salinity and infiltration and their inter relation were aoalyed by using the theoretical method of serial analysis in this paper. Satisfactor results were obtained by the method. The maximun entropy spectral method ometry estimation used had a high resolution ratio and could expose: the superior eperiod. The intwer relations among the series were exposed by the mutual spectral analysis. The resualts obtained by a multidimension AR(p) model could fit well with the mtaswied results.