The pulse laser damage thresholds of GaAs target irradiated by three different CW laser power density were given after the experimental investigation on the combined damage of the GaAs target with 1.06μm CW and pulse laser irradiation. The results show that combined damage thresholds were less than the separate ones. The surface temperature distributions and temperature rise at the surface center caused by CW laser irradiation were calculated according to two-dimension heat transfer equation. In the end, the experimental and calculated results were analysed, with the emphasis on the comparision of combined damage and separate damage．