The sintering behavior, microstructure and microwave dielectric properties of Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with CuO have been investigated. Among the range of additions, 3 wt％ CuO was observed to perform most satisfactory for acting as a sintering aid. The dielectric properties were found to strongly depend on the sintered densities. The dielectric constant increased with sintering temperatures, while the Q${ imes}$ $f_{0}$ value affected by second phase. For Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with 3 wt％ CuO sintered at 100$0^{circ}C$ for 2 h, the dielectric properties with an $varepsilon$$_{r}$ value of 56, a Q${ imes}$ $f_{0}$ value of 3,500 GHz and a $ au$$_{f}$ value of 10 ppm/$^{circ}C$ were obtained and suggested for practical applications.cations.ons.ons.ons.