This paper presents the results of an investigation into the pull-out capacity characteristics of screw anchor piles. Theoretical background of screw anchor pile (SAP) was first discussed. A series of reduced-scale model tests were performed on a number of cases with different SAP geometries such as pitch and diameter of screw as well as relative density of the model ground. The applicability of the pull-out capacity prediction equations were also examined based on the test results. It was shown that the pitch of screw has negligible effect on the pull-out capacity, while the diameter of screw has relatively large effect on pull-out capacity under a given condition. Practical implications of the findings from this study are discussed in great detail.