In order to realize the digital control of phase shifting in Electronic Speckle Pattern Interferometry (ESPI), a method for out-of-plane displacement measurement by applying phase shifting based on optical vortex was proposed. In the experiment, vortex beam is generated by a Reflective Liquid Crystal Spatial Light Modulator (LC–SLM), and the phase shifts are obtained by rotating the vortex beam around its axes. Vortex beam which is used as reference light interferes with object light, and the out optical field is captured by a CCD camera. Four speckle patterns with phase-step π/2 are captured by the CCD before and after the deformation, respectively. The phase difference of the deformed object is obtained by unwrapping. Experimental results demonstrate the efficacy of the proposed method for out-of-plane displacement measurement.