Rapid urbanization profoundly affects global biodiversity. To date, numerous studies have been conducted on how urbanization affects aboveground flora and fauna. However, the effects of urbanization on the diversity and composition of belowground biota, such as nematodes, remain unknown. To address this knowledge gap, high-throughput sequencing was used to investigate the impact of different urbanization levels (urban regions, suburban regions, and ecoregions) on soil nematode communities in Baoding City, China. Our results revealed that the soil nematode communities in urban regions exhibited a lower alpha diversity (richness) and a higher beta diversity than those in ecoregions. This is potentially due to the loss of native specialist species in urban regions and higher environmental heterogeneity of urban regions compared with other regions. Random forest and network analysis revealed that heavy metals, soil properties, and a few representative nematode taxa mainly contributed to the variations of nematode community diversity among regions with different urbanization levels. The main drivers of variations include lead content and the Tylenchida order in urban regions, cadmium and the Rhabditida order in suburban regions, and total organic carbon and numerous taxa in ecoregions. It is not difficult to find that soil heavy metal pollution originating from human activity plays an important role in the variations of soil nematode communities. Structural equation models revealed that the diversity of the soil nematode community was altered by urbanization directly or indirectly via either bacterial diversity or nematode abundance, and the pathways were contrasting for different regions. Overall, our results indicated that urbanization reduced soil nematode diversity and changed the composition of soil nematode communities, likely leading to biodiversity loss, and the establishment of ecological preservation areas maybe help improve the situation.