<p>The changes in bone mineral density (BMD), bone structure, and bone size at the proximal humerus with aging, which can lead to fragile fractures in men, are not well understood. This study aimed to investigate age-related changes in the skeletal properties of the surgical neck of the humerus in men. We conducted a cross-sectional cohort study involving 193 Chinese men, divided into three age groups: Group I (20–50 years), Group II (51–64 years), and Group III (≥ 65 years). Bone mass, structure, and geometric properties were evaluated using quantitative computed tomography (QCT). Bone mineral density at the surgical neck showed the strongest negative correlation with age. However, cortical thickness did not significantly correlate with age. Medullary diameter, perimeter, and area increased by 2.68%, 2.72%, and 5.68% per decade, respectively. Periosteal expansion was evidenced by a 2.77%, 2.80%, and 5.57% per decade increase in periosteal diameter, perimeter, and total area. Significant differences in periosteal and medullary parameters were observed between age groups. Section modulus and second moments of area exhibited significant linear associations with age. Notably, these indices did not differ significantly between men aged 20–30 years and those over 80 years. Cortical thickness and periosteal diameter were most strongly associated with section modulus and second moments of area. The study demonstrated that periosteal expansion progresses with aging, paralleling the decline in BMD. Importantly, geometry-related bending and torsion resistance of the surgical neck were not significantly diminished in older men.</p>