In order to investigate the load distribution and settlement characteristics of large scale piled raft foundation in practical engineering, a nonlinear analysis method for the rigid piled raft foundations under vertical loading is presented based on the pile-soil-raft interactions theory. Four types of interactions, i.e., pile-soil interaction, pile-pile interaction, raft-soil interaction and raft-pile interaction, are considered for the pile-soil-raft interactions herein. The hyperbolic attenuation pattern of soil modulus is considered for the nonlinear elasto-plastic analysis. Based on the comparisons with the field tests of piled raft foundation with different scale，a method to determine the soil parameters is specified, and the validity of the proposed method is verified by comparing the settlement and load participate ratio with the measured results. The optimized analysis of a piled raft case shows that the number of piles can be reduced significantly, provided that the load distribution of the raft is considered, and when the pile number is reduced to 1/3 of the original, the piled raft settlement does not increase remarkably.