We report a continuous production of Perovskite-type metal oxide nano-phosphor CaTiO3:Pr by hydrothermal synthesis using a flow type reaction system. Aqueous mixing solution of Ca(NO3)2, TiO2sols, and Pr(NO3)3 were used as stating materials. Reaction temperatures and pressure were set to 200 to 400 °C and 30 MPa, respectively. Characteristics were performed by powder X-ray diffractometry, transmission electron microscopy and spectrophotometer. We investigated the effects of the reaction temperature on crystal structure, particle size and photoluminescence properties. From the results, the particle obtained at 400°C was single crystal with around 20 nm in a diameter and had Perovskite structure. The particles shows a typical red emission peak at around 612 nm, which is assigned to the transition 1D2 → 3H4 of Pr3+. The intensity of the red luminescence increased with reaction temperature and then it showed the maximum at 400°C of supercritical water condition.