High Curie temperature bismuth-layered lead-free piezoelectric ceramics based on Na_0.5Bi_4.5Ti_4-xCo_xO₁₅ （x=0， 0.025， 0.050， 0.075） were prepared by conventional solid state reaction method. The crystal structure， fracture morphology， oxygen vacancy status， as well as the dielectric， piezoelectric and ferroelectric properties of the samples were characterized by XRD， SEM， EDS， XPS and related electrical parameter testing systems. The influence of different doping contents of Co on the ceramic properties was investigated. The results show that when the doping content of Co is 0.050， the sample exhibits a single and uniform phase composition， with a lamellar structure and high densification. The piezoelectric constant is 34.7 pC/N. The dielectric loss is only 0.30% and the Curie temperature is 672 ℃. The high temperature resistivity at 500 ℃ is 1.62×10⁷ Ω•cm. Meanwhile， the sample demonstrates excellent temperature stability， suggesting that the doped Na_0.5Bi_4.5Ti_3.95Co_0.05O₁₅ ceramic has potential market applications value in high-temperature and high- frequency fields.