Based on energy equation,a one-dimensional model was used for the evolution of the temperature distribution in the GaAs target bombarded by Intense Pulsed Ion Beam (IPIB).The numerical simulation was completed according to a fitting result from the waves of the ion diode magnetically insulated and the ion current density detected by Faraday cup at the focus region of the Russian TEMP type accelerator.The parameters of the IPIB are:ion beam composing of H+ 70 %,C+ 30 %,with average value of pulsed voltage 300kV,the maximal peak of current density of the beam 260 A/cm2,pulsed width 60 ns.Considering GaAs chemical properties at high temperature,we created the model to describe the molten process,simulation on the GaAs speciality below the melting point,and Ga speciality above the melting point because liquid As easily evaporates.The numerical simulation results reveal the temperature distributing in the samples and provide quantitative informations of the first melting time at 10ns and melting layer thickness 2.88 μm after one pulse.