Silicon nitride materials with low dielectric properties were prepared using nano and micron silicon nitride powders as raw materials and the green bodies were sintered with cordierite as sintering additive in flowing nitrogen. The additives of cordierite powders prepared by sol-gel method and solidstate reaction method could greatly decrease the sintering temperature. The dielectric constant of materials decreased as sintering temperature fell, whereas the strength showed relatively low as the low sintering temperature. XRD analysis showed the main phase of material was Si2N2O, which indicated that the Si3N4 could be integrated with SiO2. Porous structures were observed by SEM, showing compact sintering cannot be achieved at these temperatures, explaining the low strength.