The invention provides a method for measuring solid material surface roughness by using elliptical polarization parameters, and relates to a method for measuring solid material surface roughness. Objectives are to solve problems in the prior art that an atomic force microscope in an existing measuring method is slow in speed, a scanning electron microscope requires a measured sample to be conductive, and precision of a light-section microscope is not high. The method is realized through the following technical scheme: step 1, performing analog computation on rough surface characteristic parameters of different solid materials, that is, through a three-dimensional finite-difference time-domain method to obtain space electromagnetic field distribution of the near-field of a solid material rough surface; step 2, through near-to-far-field transformation to obtain a complex electric field E of a far field, calculating radiation polarization characteristic on a mirror reflection direction, and establishing a database; step 3, after a solid material is produced, measuring the optical elliptical polarization parameters on the surface of the solid material, and comparing with the database, to obtain root-mean-square roughness and correlation length. The method is applied in the field of measuring surface roughness.