Abstract: The properties of the laser cladded layers depend on the microstructure to a great extent.It is highly important to predict and control the microstructure changes and thus the grain morphology evolution of the laser cladded layers must be studied.In this paper,Hunt model and Gumann model of the columnar to equiaxed transition in laser cladded metal layers are reviewed.Grain morphology can be predicted through obtaining the critical temperature gradient and solidification velocity on the basis of the models and it is advantageous to choose experimental parameters.Domestic researches on the columnar to equiaxed transition model are simply introduced.The problems to be faced and tendency in the field are pointed out.