The influences of ultrasonic field on temperature field, flow field and the melt pool morphology during laser melting are studied through numerical simulation and experiment. A new three-dimensional mathematical model describing the ultrasonic field and temperature field in the laser melting with ultrasonic vibration is developed. The temperature field and flow field of the laser melt pool variation are analyzed systematically by the finite volume method for coupled ultrasonic field and temperature field in laser melt pool simulation analysis. The results show that the temperature of molten pool under the effect of ultrasonic field is slightly lower than that of not applying ultrasonic field. The flow rate increases by 72%, but the effect of ultrasonic field does not change the circulation tendency of Marangoni flow without ultrasonic. The width of melt pool increases by 0.5 mm and depth reduces by 0.1 mm under the influence of ultrasonic field. It′s verified that the numerical simulation results are consistent with actual situation by laser melting experiment basically.