In order to achieve accurate temperature measurement in high-temperature environments, a measurement method based on femtosecond fiber Bragg gratings (FBG) is proposed, utilizing the outstanding thermal stability of FBG fabricated by femtosecond lasers. A FBG central wavelength-temperature model was established based on the dependence of thermal optical coefficient and thermal expansion coefficient on temperature. Since there is no analytical expression for the model, the temperature-central wavelength working curve is fitted by using the single point specific solution of central wavelength-temperature and quartic polynomial. Based on this working curve and pre annealing (1 000 ℃, 20 h) FBG, temperature measurement experiments were conducted from room temperature to 900 ℃, and the results showed that the maximum measurement deviation was less than ±2 ℃. This method only needs to calibrate a single point central wavelength-temperature to achieve accurate temperature measurement over a wide temperature range. It is simple and effective, and has important research and application value in the fields such as aerospace, nuclear power metallurgy, etc.