The effect of x wt% CuO-y wt% V₂O 5 content on the microwave dielectric properties of (Pb 0.45 Ca 0.55 )[(Fe 0.5 Nb 0.5 ) 0.9 Sn 0.1 ]O₃ (PCFNS) ceramics was investigated. In order to decrease the sintering temperature and use as a Low Temperature Co-firing Ceramics (LTCC), CuO-V₂O 5 are added in the PCFNS. The bulk density, dielectric constant (e r ) and quality factor(Q · f o ) increased with increase in CuO content within a limited value. The microwave properties were degraded with increases in V₂O 5 content. The temperature coefficient of the resonant frequency (τ f ) of PCFNS was shifted to positive value abruptly with increasing the V₂O 5 content, while the τ f was slightly shifted to positive value with increasing the CuO content. The optimized microwave properties, e r =88, Q · f o =6100 (GHz), and τ f = 18 ppm/℃, were obtained in (Pb 0.45 Ca 0.55 ){(Fe 1/2 Nb 1/2 ) 0.9 Sn 0.1 }O₃ with 0.2 wt% CuO 0.05 wt% V₂O 5 and sintered at 1000℃ for 3 h. The relationship between the microstructure and microwave dielectric properties of ceramics was studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).