Double-exposure method is a technique in which a standard object is exposed twice and the wavefronts reflected from the object before and after the change are recorded on the same hologram at different time. As a result， two first-order interference fields are produced without the introduction of a reference plane. A second-order interference field is created by the two wavefronts during reconstruction process. The relationship among the second-order interference field， small displacement， light phase change and rotation angle is invesgated by using experiments combined with computer simulation. The small displacements of rigid diffuse objects are measured using double-exposure hologram. Experimental results show that the stripes of the objects appear in the vicinity of the localized space curves， and their sharpness depends on the aperture of the observing system.