A method for correcting the thermoelastic effects on performance parameters of a telescope on board a space satellite, comprises a first step prior to the flight of the satellite consisting in determining, a priori, a correction of the thermoelastic effects by using a prior model of variations of the thermoelastic effects on the orbital scale and an algorithm for determining correction fed by programming data of the space satellite, and a second step carried out in flight, based on the correction determined a priori, consisting in establishing control messages of correction means for correcting the performance parameters of said telescope.