In allusion to the difficulty to use the existent pyrometer in the high temperature and vacuum,this paper present a qualitative analysis and a quantitative analysis for the radiation energy transfer in the optical fiber.And based on the results of the above analysises,the modal and the formula of total coefficient about energy transfer by optical fiber and temperature measurement are also established.Finally,the designing and calculating example of this radiator is given and the feasibility of this measure is proved.The function of the existent pyrometer is extended.