Abstract: In order to obtain the composite foundation practical work state, which acts by cushion adjusting and by pile and soil bearing load together, single pile composite foundation static loading testing set is designed. It is used to test composite foundation characteristic value of composite foundation bearing capacity, characteristic value of pile and characteristic value of soil in piles containing cushion. This set can obtain the settlements of pile, soil in piles, and composite foundation and load severally, and can make the results of distribution of load in piles and soil in piles under composite foundation load, and can acquire the pile-soil stress ratio, which displays working mechanism of composite foundation. At last, through the practical testing used single pile composite foundation static loading testing set, the composite foundation, pile and soil in piles working state are discussed respectively, which can be used practically in scientific research, practical design and technical testing of composite foundation.