The utility model provides a variable cross section CFG stake composite foundation static test self -balancing composite set, the device include that model box, load exert system, data measurin system, ystem installation is exerted in model box top to the load, and it is internal that the mold box is placed in to the stake of variable cross section CFG and simulation ground sill, and the load is exerted the system and is included force applying device, force transfer device, force applying device upper portion is connected with the force transfer device that the load counter -force was used, and force applying device adopts the compound foundation surface of the internal variable cross section CFG stake of load mode proof box downwards step by step to exert load, comes balancedly through the dead weight of model box, the sill dead weight of simulation ground, variable cross section CFG stake dead weight. The utility model provides a research variable cross section CFG stake composite foundation failure mechanisms, confirm that load design value in -process needs fixed counterforce device or a large amount of problem of carrying of piling, adopt manual formula screw jack to carry out loading step by step, the load size is forbidden the problem by artifical manual control jack, the ftercompction that can not take place hand jack.