In this work, the low-permittivity CaCoSi2O6 ceramics were prepared through solid-state reaction method. With the increase of sintering temperature from 1125 degrees C to 1200 degrees C, the dielectric constant increased, the quality factor and the vertical bar tau(f)vertical bar increased first and then decreased at 1200 degrees C. Rietveld refinement and complex chemical bond theory were carried out to investigate the relationships between the bond ionicity, lattice energy, bond energy and dielectric constant, quality factor, the temperature coefficient of resonant frequency of the low-permittivity CaCoSi2O6 ceramic. The optimum microwave dielectric properties were obtained when the sample was sintered at 1175 degrees C for 2 h: epsilon(r) = 6.04, Q x f(0) = 12457 GHz and tau(f) = -18.91 ppm/degrees C.