A heave-resistant design method of expansive soil composite pile foundations at the bottom of a subgrade comprises the steps of determining a design target, surveying geotechnical parameters, initially selecting and determining composite pile foundation parameters, determining calculation parameters, calculating a heave amount of the top surface of the subgrade, and determining composite pile foundation design parameters. The heave-resistant design method of the expansive soil composite pile foundations at the bottom of the subgrade comprehensively considers three factors of a composite pile foundation replacement function, a side surface anchorage function and a subgrade soil-filling energy-dissipation effect. The heave-resistant design method is proposed on the basis of taking the heaveamount of the top surface of the subgrade as a design control target, and is capable of scientifically and reasonably carrying out the heave-resistant design of the expansive soil composite pile foundations, effectively controlling the number of foundation reinforcement engineering, achieving the goal of reducing the railway construction cost, making up for the blank of specifications and adaptingto actual engineering needs.