The morphological structure of limb bones can reflect important information, i.e. human evolution, adaptive behavior of ancient populations and living environment, and vice versa. Most of these studies are based on “Bone Functional Adaptation” and “Beam Model”. Based on these, physical anthropologists have done a lot of research on femora of ancient populations with different lifestyle. However, there have been no related published studies about the femoral differences between agricultural and nomadic populations. Here, we provided detailed comparative assessment of femora from two archaeological sites, i.e. Tuchengzi and Jinggouzi from Inner Mongolia, with agricultural and nomadic lifestyle separately. Specifically, we analyzed diaphyseal structure of femoral three-dimensional visual digital model using methods of cross-sectional geometry. There was significant difference between Tuchengzi and Jinggouzi population. The mean level of femoral robusticity of Tuchengzi agricultural population was found to be larger than that of Jinggouzi nomadic population. The Jinggouzi female sample was significantly less robust than other groups, which should be correlated with the habitual riding behavior. The soldier status of Tuchengzi male sample may lead to the relatively larger variation range of femoral biomechanical index than that of Jinggouzi. It also indicated that the behavior information reflected by Tuchengzi male did not represent the typical agricultural population, but a mixture activity pattern. In terms of gender division of labor, the habitual riding behavior made the mechanical loading on bilateral femora relatively symmetry and similar cross-sectional shape of femoral midshaft, which led to little gender difference of femoral bilateral asymmetry in Jinggouzi sample. However, the males from nomadic population are involved in hunting behavior, which induces the significantly more robust femora that that of female. Compared to the slender femora of females in nomadic population, females in Tuchengzi sample, as the representative of the typical agricultural population, had almost the same robusticity as males of the same group, meaning that the agricultural females were more active in daily life. This also led to the relatively small gender difference of femoral robusticity within Tuchengzi sample. However, there is distinct difference of cross-sectional shape on femoral midshaft between Tuchengzi males and females, which suggesting that the activity pattern is significantly different between males and females of Tuchengzi sample.