In order to form an effective interphase in a polymer composite, the preparation and characterization of silane structure on particle surface and in the interfacial layer in the composite are reviewed. The polycondensation of silane is affected by the concentration and pH of silane solution and the pH of inorganic particle. Pulsed 1H nuclear magnetic resonance (pulsed NMR)analysis is useful to characterize the structure of silane layer on the particle surface. It is found that the linear chain structure formed from dialkoxy type silane is flexible, whereas the network structure formed from trialkoxy type silane is rigid. To form an effective interphase, the linear chain structure formed from dialkoxy type is more useful than the network structure formed from trialkoxy type in the silica-filled rubber composites. The pre-treatment method and the integral blend method are compared in the silica-filled rubber composites. As a result, the dialkoxy type is found to be suitable for the pre-treatment method, whereas the trialkoxy type is suitable for the integral blend method. In the pre-treatment method, the linear silane chains form entanglements with the rubber chains in the interfacial region and improve the reinforcement effect. In the integral blend of trialkoxy type, the formation of the silane network and the entanglement proceed simultaneously during the preparation process and a well-entangled interfacial region is formed. Pulsed NMR analysis for the silica-filled unvulcanized rubber composites is useful to analyze the interfacial layer in the composites. The surface treatment of CaCO3 with a mixture of amino and mercapto functional silanes is found to be useful to improve the reinforcement effect in rubber/CaCO3 composites.