<p>As a member of <i>Acinetobacter calcoaceticus-baumannii</i> complex, <i>Acinetobacter pittii</i> has been an emerging concern in nosocomial infection due to its increasing prevalence and multidrug resistance (MDR). However, its population structure remains broadly unknown, hampering efficient tracing of its transmission and evolution. In this study, we developed a distributed core genome multilocus sequence typing (dcgMLST) for <i>A. pittii</i> based on 750 genomes and employed it to map the genetic landscape and evolution of <i>A. pittii</i>. The results demonstrated that two hierarchical clustering (HC) levels effectively correspond to genetic diversity from species (HC1100) to natural populations (HC450), as well as that a predominant lineage, HC1100_4, accounts for 33.9% of <i>A. pittii</i> strains. Subsequent analysis revealed that specific gene gain and loss events within HC1100_4 are linked to adaptations to environmental stress. Moreover, we identified a cluster of multidrug-resistant plasmids PT_712 responsible for the dissemination of <i>bla</i>_NDM-1 genes within the genus of <i>Acinetobacter</i>. This study provides a framework for characterizing genetic diversity, evolutionary dynamics, molecular population distribution, and tracing of <i>A. pittii</i>, which has the potential to improve infection control strategies and public health policy.</p>