Abstract: This paper presented the quasi stationary finite element model to describe the free surface situation of the melted pool by laser processing.It is show that Marangoni force and vapor pressure are two internal factors to influence the deformation of the free surface.When the temperature of the melted pool is lower than boiling point,the first one is the main effect,and the gravity will significantly influence the surface morphology.The main outer factor is the gas flow.The strength and the distribution of the gas flow.The strength and the distribution of the gas flow will too affect the surface morphology obviously.