High temperature platinum resistance thermometers(HTPRTs) were designed and fabricated using a synthetic sapphire single crystal as sensor former, insulation and protection tube, and its characteristics was investigated. Several fixed points measurement showed that the sapphire HTPRTs were satisfied with the ITS-90 criteria as the interpolating thermometer. The temperature-resistance characteristics of HTPRT was fitted to the quadratic relationship in the temperature range from $500^{circ}C$ to $1500^{circ}C$. The reproducibility of Cu freezing point realized using the sapphire HTPRT was ${pm}19.2;mK$. The insulation resistance of the HTPRT exponentially decreased as temperature increased, and showed to $63;k{Omega}({sim}31.5;mK)$ at $1500^{circ}C$.