Abstract: The deformation mechanism of sand around plate anchors during uplifting is essentially important for the reliable prediction of their ultimate bearing capacity in sand. First, a series of model tests are conducted. The digital image correlation method is used to measure the sand deformation fields during uplifting of anchors. The deformation fields show that a pair of shear zones accompanied by dilatancy are formed. The stress level, friction angle and dilatancy angle control the shape of the failure surface, thus affecting the bearing capacity of the plate anchors in sand. A prediction model for uplift force is developed based on the sand deformation mechanism around an uplifting plate anchor. The relationship among the dilatancy angle, the relative density and stress level established by Bolton is introduced to develop the theoretical formula. The comparison between the theoretical and test results is conducted. The theoretical results show good agreement with the test results.