Objective To investigate the mechanism of occurrence and rehabilitation of heel pain, so as to provide a theoretical basis for the effectiveness of heel pain treatment. Methods The CT and MRI data acquired from feet and knees of patients with heel pain were reconstructed to establish the bone-muscle composite finite element model. Based on the established model, the effect of calf muscle contracture on biomechanical properties of the foot and ankle was simulated by using the finite element method . Results When the calf muscles produce upward lifting power, plantar pressure was transferred from the heel area to the forefoot area, and there was no significant difference in pressure distribution by different combination schemes of muscle forces. The strain of the plantar fascia was increased, with stress concentration on the calcaneus surface. Under 240 N force, the peak stress at the Achilles tendon attachment position and the calcaneus nodules was up to 10.82 MPa and 11.2 MPa, respectively. Conclusions The stress concentration in calf muscles and Achilles led to the changes in biomechanics of the ankle, which resulted in heel pain. The method of improving the overall biomechanical environment by releasing concentrated stress to restore the position of the bones and joints of the ankle joint is the mechanism for rehabilitation of heel pain.