Introduction: Recent studies have shown that inflammatory patterns of nasal polyps from patients with chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) in East Asia have changed over time. However, to date there is a marked lack of similar data for CRSwNP in Northern China. This study thus aimed to assess the changes in the clinical and histological characteristics of CRSwNP patients from Northern China over the past 2-3 decades. Methods: This was a retrospective study, which examined data from 2 groups of 150 CRSwNP patients each, who had undergone endoscopic sinus surgery in Beijing Tongren Hospital from 1993 to 1995 (group A) and from 2015 to 2019 (group B). All relevant data for demographic, clinical, and histological parameters were collected for each patient from the 2 groups and compared for overall changes between the 2 groups. Results: The comorbidity of CRSwNP and asthma increased over time and the cellular phenotype of CRSwNPchanged significantly; in particular, the proportion of eosinophil-dominant CRSwNP increased, lymphocyte-dominant and plasma-dominant CRSwNP decreased significantly, and the proportions of neutrophil-dominant and mixed CRSwNP were not altered. The rate of polyp recurrence increased in CRSwNP but did not in eosinophilic CRSwNP. Smoking and age did not significantly impact the inflammatory patterns of CRSwNP. Conclusions: The inflammatory patterns of CRSwNP patients have changed and comorbidity of asthma significantly increased in CRSwNP patients in Northern China over the past 2-3 decades.