Abstract: In this paper the correlation between electromagnetic parameters and absorption about dielectric-type electromagnetic wave absorber in S band are researched on the basis of electromagnetic wave absorption theory.Under the conditions of intended high-reflectivity,the electromagnetic parameters are optimized,and the ideal complex permittivity region is determined is determined to achieve the intended reflectivity under a certain frequency bands,and then proper materials for preparation of high-performance absorber are introduced.The research may have on important guiding significance for absorbers design and preparation.