This study aimed to review our experience with the clinical characteristics and management of deep neck infections (DNIs) and determine the changing trends of their characteristics over time in southern China. Patients diagnosed with a DNI between January 2009 and December 2018 were screened retrospectively for their demographic characteristics, etiology of infection, site of infection, microbiology, treatment, and complications. In total, 127 patients were included: 41 (32.3%) were treated between 2009 and 2013 (group A), and 86 (67.7%) were treated between 2014 and 2018 (group B). The most common site of infection in group A was the parapharyngeal space (15 patients, 36.6%), while that in group B involved multiple spaces (36 patients, 41.9%). The leucocyte count (×10⁹ cells/L) was 13.23 ± 4.19 in group A and 16.04 ± 4.33 in group B (p < 0.001). Streptococcus viridans was the most common bacteria in both groups. The mean hospital stay was 21.46 ± 33.09 days in group A and 10.44 ± 6.19 days in group B. The rate of diabetes mellitus (DM) in group A was lower than that in group B (8/41 and 33/86, respectively; p = 0.034). Airway obstruction was the most common complication in both groups. DNIs are more likely to show multi-space involvement, affect more DM patients, and be associated with higher leucocyte counts over time. We infer that the duration from morbidity to admission and that from admission to operation play roles in the successful management of DNIs, possibly causing fewer complications, lower mortality rates, and shorter hospital stays. DM patients require increased attention.