In this paper, the digital image correlation method for the analysis of 3-D displacement field is firstly presented. The 3-D displacement field caused by internal microstructures evolution is obtained by correlative calculation of digital images taken before and after deformation of the object. The 3-D searching window, correlation function and the fitted function of correlation coefficient are obtained. The numerical simulation results confirmed this technique. The precision of displacement measuvement is 0.02 pixel.