Abstract: The analytical expression for the temperature rise of a passive optical component under the irradiation of multiple short pulses with different amplitudes and intervals has been derived from the Fourier heat transfer equation.Calculations and analyses have been made for the case that the radiation is a train of periodically repeated pulses.The relations between the distribution of temperature rise and such factors as the number of pulses,pulse intervals,pulse flux densities have been discussed.Finally the phase distortion induced by the temperature rise has been estimated.