With the intensification of the aging population trend, the biomechanical characteristics of walking in the elderly have become a crucial research focus in the fields of health management and rehabilitation. Understanding the biomechanical features of lower limb posture control during walking in different age groups of the elderly is essential for a better comprehension of gait changes, prevention of lower limb injuries, and the formulation of effective rehabilitation strategies. Providing valuable scientific insights for advancing research in elderly health management and rehabilitation, in order to explore this area. Investigate the impact of age-related changes on the biomechanical characteristics of gait in middle-aged and elderly populations, with the aim of reducing the risk of falls and injuries during walking. A total of 60 participants aged 40 ~ 49 and 50 ~ 59 were recruited, including 30 males and 30 females. Kinematic and kinetic data were collected using motion capture equipment, including the Codamotion infrared capture system, ATMI three-dimensional force platform, and Footscan pressure plate. Statistical analysis of all data was conducted using Cohen's effect for meaningful interpretation of the results. The experimental results show as follows. During the transition from heel contact to full foot contact, elderly women exhibited the maximum angular change in left knee flexion at 11.22°, while elderly men showed the maximum angular change in right hip flexion at 5.99°. In the initial contact phase, both sides of the lower limbs in middle-aged and elderly women exhibited a moderate effect size difference (d=0.5, d = 0.77), and during the entire foot contact phase, there was a moderate effect size difference in both sides of the lower limbs in elderly women (d = 0.62). In elderly men, the bilateral difference in the Z-axis directional feature F₁ during walking demonstrated a moderate effect size (d = 0.714). These findings suggest that with increasing age, there is an enlargement in the bilateral foot eversion, leading to increased instability during walking. Gait changes are influenced by gender differences, suggesting the need for tailored training and interventions when devising personalized rehabilitation and prevention strategies. Additionally, age-related variations in foot pressure and impact correlate with age, highlighting the importance of strengthening foot muscles to reduce foot injuries and improve gait stability.