Abstract: In order to study the influence of the backfill characteristics of the large karst area on the load transfer of the pile foundation and to improve the safety and economy, considering the characteristics of the side friction resistance of the pile back and the pile in the large karst area, based on the exponential load transfer function, the method for calculating the load-settlement curves of backfill piles in large karst area is obtained. The method is verified by the existing research results and engineering examples. The results show that the proposed method is in good agreement with the actual project. Based on this method, the influence of parameters on the load- settlement curves of karst piles is analyzed. The results show that the load-settlement curves of pile foundation increase with the axial strain, particle size of gravel and pile parameter α_b, and the ultimate bearing capacity of the piles increases with the increase of the axial strain and pile parameter α_s and decreases with the increase of the particle size of gravel.