Laser rapid solidification experiments have been performed on Cu31.4%Mn alloy to investigate the response of microstructure pattern and cellular spacing selection to the variation of growth rate.With increasing growth rate,microstructures go from light band to elongated cell,regular cell,then elongated cell and planarlike structure,and finally to absolute stability planar in turn.Experimental results show that there is a distribution range in cellular spacing under the aser rapid solidification condition,the distribution range and the average spacing decrease with the increase of the growth rate.The maximum,λmax, minimum,λmin,and average primary spacing,A,as functions of growth rate vs, can be given by λmax=682v-033s，λmin=289v-028s and =435v-031s,respectively.The experimental results are compared with the HuntLu numerical model for rapid cellular/dendritic growth,and a reasonable agreement is found.