The sapphire optic fiber thermometer for high temperature is described.The sapphire optic fiber is suitable for high temperature measurement because of its wonderful high temperature physical and chemical performance,which can be used for radiation optic fiber temperature sensors.A sapphire fiber thermal probe with Cr3+ion-doped end is grown by using the laser heated pedestal growth method.A laser is used to heat a small pedestal,so that fluorescence-temperature-responsing materials like a small ruby crystal optic-fiber will grow on the top of the sapphire optic-fiber,which can be made into a compact-structure,high-temperature and stable-function sensor head.Though the fluorescence life measurement,the corresponding temperature can be measured.According to the surface temperature,the inner temperature can be obtained by the temperature field.It can be used in measuring the steel fluid of the tundish in continuous cast steel machines.Experimental system of the thermometer and the preliminary experimental result are presented.The experiment results shows that it can realize non-touched measurement and has high precision.