Glass fiber fabric-reinforced epoxy composites (GEC) have some weakness on both thermal insulation and sound absorption insulation, which are very important for many application areas such as aircraft, train, and so on. The main aim of this study is to improve both sound absorbent and thermal insulation properties of GEC by incorporating different fillers such as hollow glass microspheres (HGMs), polystyrene (PS) microfiber membrane, and PS solution. Results show that incorporation of PS solution into glass fiber fabric epoxy composite (GEC-PS) provides higher sound absorption coefficient leading to an increase in the max SAC value from 0.1 to 0.4 and improvement in thermal insulation by decrease of thermal conductivity coefficient of GEC from 0.48 to 0.448 W/mK. Thermal insulation properties of GEC were improved by the use of PS microfiber membrane, which decreases the thermal conductivity coefficient of GEC from 0.48 to 0.438 W/mK. HGM did not improve both the thermal insulation and sound absorption insulation properties of GEC due to the agglomeration.