Focusing on the unneglectable error of testing results for the rough surface material by the PG model, the basic model assumption, modeling process, parameters inversion and fitting results are analyzed, and the cause for the error is found out. Taking the physical fact that evanescent wave existing in the fine structured surface as the basis, and ignoring the penetration depth and phase delay, a new assumed surface configuration which is integrated into micro-hemispheroid is created. Then, a new reflectance function is built, the inner scatter function is refined, and a new pBRDF is established. Illuminated by full spectrum light in a laboratory, the spectrum testing data of dual-directional reflectance for surface is acquired, and the performance of the PG model and the new model is compared. The result indicates that the new model error in the radiance and the DOLP is respectively about 35% and 59% of that of the PG model.