Abstract: In the construction process of docks，due to limitations of mountain site，the large diameter socketed short piles were used in those areas． But the in-situ experimental study was lacking under horizontal load． The top-loading method was used to test and the horizontal bearing characteristics of short large-diameter rock-socketed piles were analyzed，including load-displacement curve，horizontal displacement distribution，the distribution of the bending moment and shear force along the pile legth． The results indicated that the relationship between horizontal load and displacement of short pile was linear distribution，and the increase of length was more favorable to improve its horizontal mechanical properties． From the lateral deformation of pile，the deformation occured mainly in the upper soil，surface soil density and the size of pile had a significant influence on its lateral deformation． From the distribution of internal forces of piles，the maximum bending moment was located in 6 m below the surface and maximum shear mainly distributed near the surface．