Investigation of the phase change on Fourier transform plane caused by a moving object shows that it is possible to measure a 3-D displacement vector using comparison of the phase-change recorded on a double exposure hologram. Based on it, a novel approach for measuring a 3-D displacement vector is described here. Theoretical analysis shows that the problems usually appeare during interpreting the interferograms of a conventional double exposure hologram for 3-D, displacement measurement have been effectively avoided. Experimental results are well coincident with theoretical analysis. Quantitative calculation method ia also presented.