To study the application of laser shearing speckle interferometric vibration measurement technology in acoustic resonance landmine detection, we present an experimental and theoretical study of the method for laser shearing speckle interferometric landmine detection based on time-average. The relationship between the out-of-plane displacement gradient generated by the sound wave on the ground and the phase change of the shearing interference laser is analyzed. A high-power loudspeaker is used as the source of sound wave excitation, and the laser shearing speckle interferometric vibration measurement system is used in landmine detection experiments to investigate the changes of laser shearing speckle interference fringes under different experimental conditions such as sound wave intensity, detection target, buried depth, and soil environment. The study reveals that it is feasible and effective to use laser shearing speckle interferometry to detect landmines, and it provides a theoretical and methodological basis for realizing the rapid scanning of acoustic-optic landmine detection.