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.