<p>Individuals with chronic ankle instability (CAI) often exhibit abnormal biomechanical changes during gait, which are thought to accelerate cartilage and joint degeneration. However, the current understanding of changes in joint contact force and muscle force during gait in individuals with CAI remains inadequate. In this study, 10 individuals with CAI and 10 healthy controls were recruited for walking biomechanics analysis, and a five-segment musculoskeletal foot model with 14 degrees of freedom was constructed. The foot model for individuals with CAI was established by adjusting the ligament stiffness of the normal foot model. The results showed that the compressive forces of the ankle joint in individuals with CAI decreased significantly by 8.32% (<i>P</i> = 0.037), while the compressive forces of the Chopart, Lisfranc, and metatarsophalangeal joints increased significantly by 19.26% (<i>P</i> = 0.048), 17.32% (<i>P</i> = 0.048), and 13.31% (<i>P</i> = 0.041) respectively. Both the anteroposterior and left-right shear forces of these joints showed an increasing trend during the heel-strike phase of the gait cycle. Additionally, the strength of key stabilizing muscles, such as the peroneus longus, peroneus brevis, and tibialis posterior, decreased significantly, resulting in a compensatory increase in the use of the tibialis anterior, extensor digitorum longus, and flexor digitorum brevis muscle groups. This study reveals changes in muscle strength and their impact on joint stability and mechanical loading in individuals with CAI, providing new insights for developing clinical intervention strategies.</p>