Background: Nasal polyps are a common health problem that can significantly impact the quality of life. Objective: To analyze the impact of allergy and peripheral eosinophils (EOS) on the morbidity of chronic rhinosinusitis with nasal polyps (CRSwNP) in Northwest China. Methods: A retrospective cohort of 323 patients who underwent endoscopic sinus surgery (ESS) for chronic rhinosinusitis without nasal polyps (CRSsNP) and CRSwNP in Xijing Hospital was studied between January 5, 2011, and January 4, 2015. All of the patients underwent an allergen skin prick test and peripheral blood EOS inspection. Detailed information regarding the impact of allergy and EOS on the morbidity of CRSwNP was collected. Potential risk factors associated with nasal polyps were explored using logistic regression analysis. Multivariate logistic regression was performed to identify independent risk factors. Results: The results revealed that EOS is an important risk factor for nasal polyps. In the univariate analysis, the adjusted OR was 2.01 (95% CI 1.08–3.72; p = 0.027). In the multivariate analysis, the adjusted OR was 2.02 (95% CI 1.08–3.76; p = 0.027). Compared to allergic rhinitis and normal EOS levels, nonallergic rhinitis and elevated EOS levels constituted a risk factor for CRSwNP (OR = 2.70; 95% CI 1.32–5.50). Compared to allergen-positive and EOS-normal status, allergen-negative and elevated-EOS status constituted a risk factor for CRSwNP (OR = 2.95; 95% CI 1.38–6.33). Conclusion: EOS is a significant factor related to the morbidity of CRSwNP in Northwest China. Elevated EOS levels occurring in the context of nonallergic rhinitis constitute a risk factor for CRSwNP. Similarly, elevated EOS levels occurring in the context of allergen-negative rhinitis are also an important risk factor for morbidity of CRSwNP.