The phenomena of heat transfer and phase change of solid argon crystal irradiated by pulsed laser was studied through the molecular dynamics simulation.In order to analyze the process of heat transfer inside the particle,the changes of velocities and locations of atoms were recorded at different time.Then the process of phases change was discussed through analyzing the variation of the number of argon molecules per unit volume.The calculation results show that when the laser intensity is low,no melting will happen.When the laser energy is increased enough,the phase change occurs and a transitional area of nanometer level instead of a clear interface is revealed between solid and liquid phase.The moving speed and moved depth of the transition zone increase with the increasing of laser intensity.