The invention provides a humanoid robot foot structure with adjustable rigidity, relates to a humanoid robot foot structure, and aims to solve the problems that a conventional humanoid robot foot structure cannot be adaptable to walking on uneven pavements, and the athletic ability of a robot is low. The humanoid robot foot structure comprises a foot bottom, a heel, a sole and a driven joint, wherein the heel and the sole are mounted on the upper surface of the foot bottom, and the foot bottom is an elastic air sac which can be inflated and deflated; the driven joint comprises a first hinge seat, a second hinge seat, a third hinge seat, hinge pins and two torsion springs, wherein the first hinge seat is mounted on the heel, the second hinge seat and the third hinge seat are mounted on the sole, and the first hinge seat is arranged between the second hinge seat and the third hinge seat; one torsion spring is arranged between the first hinge seat and the second hinge seat, and the other torsion spring is arranged between the second hinge seat and the third hinge seat; the hinge pins are mounted on the second hinge seat, the first hinge seat and the third hinge seat, and the two torsion springs are mounted on the hinge pins in a sleeving manner. The humanoid robot foot structure disclosed by the invention is used for humanoid robots.