In recent years, fiber optic distributed temperature measurement system has been widely used in the field of ambient temperature, however, in such as power plant boiler temperature from room temperature of 20 degrees Celsius to more than 600 degrees Celsius in a wide range of high temperature measurement scenarios, domestic and foreign fiber optic temperature measurement has few studies and applications. In the face of a wide range of high-temperature fiber optic temperature measurement problems, the use of special copper coated high-temperature optical fiber, built a distributed fiber optic system, with high-temperature box simulation from room temperature to 600 degrees Celsius high-temperature environment, to collect the corresponding information of reflected light. After experiments, it was found that the measured temperature deviation resolved by using the dual-channel demodulation theory formula was large, and the linear fitting widely used in normal temperature applications could not be adapted to a wide range of high-temperature scenarios.For a wide range of high temperature scenarios temperature demodulation, a variety of non-linear calibration methods are used to successfully achieve a wide range of high temperature tracking of optical fiber.