Abstract: In order to obtain dispersed phase particles with good electrorheological property,γ-amino propyl triethoxy silane (APTES) was used to modify fly-ash floating beads. Polyaniline (PAn) was coupled with chemical bonds to form core-shell structural composites, with mod-FAFB as core and PAn as shell on the surfaces of decorated FAFB (mod-FAFB). The structure and performance of PAn@mod-FAFB composites were analyzed by FTIR, SEM, digital four point probe technique and LCR dielectric spectrometer. The effect of different contents of mod-FAFB on conductivity and dielectric properties of PAn@mod-FAFB composites were researched.The results show that PAn@mod-FAFB core-shell structural composites with chemical bond graft polymerization have a relatively high electrical conductivity, and the electrical conductivity decreases with the increasing content of mod-FAFB. The relative dielectric constant is higher at low alternating electric field frequency (100-2 000 kHz), and dielectric constant of PAn@mod-FAFB composites decreases obviously with the increasing of mod-FAFB content. The dielectric loss of PAn@mod-FAFB composites is relatively low, and decreases obviously with the increasing of mod-FAFB content.