Abstract: The complete new analysis technology in the field of petroleum products’ analysis and test,dielectric spectroscopy (DS),has been studied. On the basis of the DS’ applicability to the lubricant oils’ viscosity exponent,the separate technical methods in both qualitative and quantitative aspects have been researched,and especially the partial least square (PLS) prediction model has been established. In the qualitative aspect,the multi-degree lubricant oils and single-degree ones can be distinguished. In the quantitative aspect,the correlation index between the predicted values and measured ones reach 0.999 3,and the average error is 0.616 2,and the results are satisfactory.