Abstract: Through 4 times of inclined pull-out field tests and 2 times of vertical pull-out field tests on a pile group with 3 piles composing an equilateral triangle in plane,and 5 times of vertical pull-out field tests on a screw pile,some curves of load and settlement were drawn.On the basis of the characteristics of ground deformation and the above curves,the horizontal and vertical ultimate loads were respectively estimated by the H-(Δx/ΔH) curve and the composed method of the ratio of displacement to unite load,the incremental displacement of pile head,the characteristics of ground deformation,and the group efficiency were analyzed for the screw pile group under inclined and vertical loads.It is shown that,the group efficiency of pile group is related to the working angle of load,the pull failure of the pile group is quickened by the horizontal component of force,and the ultimate load and displacement of pile group under inclined pull-out load are less than those under vertical pull-out load.