Abstract: The selection of the reaction force device is closely related to the properties of the foundation, the pile type of the foundation pile, and the site conditions.In order to obtain a more accurate horizontal ultimate load of a single pile, this paper adopts a reaction platform composed of a combined reinforced concrete beam and a reaction pile as the reaction system for applying the load.The field horizontal static load test of 3 piles was carried out, and the following conclusions were obtained:(1) The design value of the bearing capacity of the steel box girder under the main load of the new counterforce device is 295(N/mm2) , The single steel box girder has a uniform load of 12000 kN, a maximum deflection of 7.08 mm, and a bearing capacity of 1.2 times larger than the predetermined maximum test load of 3000 kN, It has enough rigidity, and the force is even and stable, no abnormal sound and no deformation during loading, It can meet the test demand and the test result is accurate and reliable；(2)Replacing the steel strand with the steel bar with the steel bar with the steel bar with small flexibility, the installation is simple and the test process is more convenient and efficient；(3)In the process of Unidirectional multi-cyclic loading, the horizontal displacement of pile top increases with the increase of load grade. When the cyclic unloading is zero, most of the horizontal displacement can be recovered, the residual horizontal displacement increases with the increase of load grade and cycle times；(4) The load corresponding to the first inflection point on the horizontal force-displacement gradient curve of the three test piles is the horizontal critical load, which is 2100kN, 1500kN, and 1500kN, respectively. There is no second inflection point, and the horizontal ultimate load is greater than 3000kN. The test results provide reference for the design and research of similar piles.