The invention belongs to the technical field of civil engineering, and particularly relates to a carrying force feature value calculation method of a variable-cross-section CFG pile composite foundation. The method comprises the following steps of calculating the carrying force feature value of a soil and weak soil layer diameter expansion section pile; calculating the carrying force feature value of the good force holding layer standard section pile; calculating the carrying force feature value of the variable-cross-section CFG group pile; calculating the single-pile carrying force exertion coefficient of the variable-cross-section CFG pile composite foundation; calculating the replacement rate of the variable-cross-section pile composite foundation; calculating the extreme carrying force feature value of the variable-cross-section CFG pile composite foundation. The method provided by the invention solves the problem of extreme carrying force calculation in the variable-cross-section CFG pile composite foundation in the foundation design; the calculation method of the soft and weak soil layer variable-cross-section pile composite foundation replacement rate and good force holding layer variable-cross-section pile composite foundation is provided; through an extreme balancing theory, the problem of variable-cross-section CFG group pile end resistance overlapping under the extreme load condition is solved; the calculation problem of the carrying force feature value of the variable-cross-section CFG pile group pile foundation in a reinforcing region is solved.