Geogrid reinforcements can effectively improve the pullout capacity of anchor plates, but the failure mechanism and influencing factors during the uplift process need to be further investigated. In this paper, a series of uplift tests was carried out on horizontal anchor plates in sand to investigate their pullout characteristics, and the influence of various factors was analyzed, including sand density, anchor embedment depth, and number of geogrids and their locations. The particle image velocimetry (PIV) technology was used to explore the deformation and failure mechanism of the sand around anchor plates. The results show that for the pullout capacity of an anchor plate is significantly enhanced by one layer of contact-type geogrid, and the reinforcing effect is better than that with non-contact geogrid. This phenomenon is associated with mobilized friction of the geogrid and the increased weight of sand within the failure surface. When two layers of geogrids are installed, the lower geogrid plays a dominant role in restricting the lateral soil deformation and homogenizing the stress distribution, and the contribution of the upper geogrid is relatively low. Whether geogrids are applied or not will alter the deformation mechanism at the anchor-sand interface. With geogrid reinforcement, the failure surface converges inward, and the shear strain distribution is more uniform.