Establishes the numerical simulation model for interaction of geocell, piles and soil around piles by simulation software FLAC3D, contrasts and analyzes the bearing capacities of the composite foundation with geocell + step variable section piles and the composite foundation with geocell + constant section piles. The results indicate that the composite foundation of geocell + step variable section piles is superior to that of geocell + constant section piles in average pile settlement, soil settlement and pile-soil settlement.