The effects of laser beam fluctuation on the temperature of material were studied for laser beam used as a thermal source. The noise source was firstly introduced into the differential equation of laser thermal conduction and the equation was solved. The temperature distribution was influenced by the noise. The fluctuation is strong at the surface of the material and weak in the deep of the material. The temperature distribution is related with laser thermal interaction process. With increasement of the laser heating time, the fluctuation increased. Moreover, The temperature distribution is also affected by the thermal conductivity K, thermal diffusivity k and absorptivity ε. Some suggestions are proposed for decreasing the influences of laser beam fluctuation.