Objective: To investigate the predictive value of blood cell ratios and inflammatory markers for adverse prognosis in patients with primary Sjögren’s syndrome (PSS) combined with coronavirus disease 2019 (COVID-19). Methods: We retrospectively collected clinical data from 80 patients with PSS and COVID-19 who visited the Rheumatology and Immunology Department of the First Affiliated Hospital of Nanchang University from December 2022 to February 2023. Inclusion criteria were (1) meeting the American College of Rheumatology (ACR) classification criteria for Sjögren’s syndrome; (2) confirmed diagnosis of COVID-19 by real-time reverse transcription polymerase chain reaction or antigen testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); (3) availability of necessary clinical data; (4) age > 18 years. According to the clinical classification criteria of the "Diagnosis and Treatment Protocol for Novel Coronavirus Pneumonia (trial the 10th Revised Edition)", the patients were divided into the mild and severe groups. Disease activity in primary Sjögren' s syndrome was assessed using the European League Against Rheumatism (EULAR) Sjögren' s syndrome disease activity index (ESSDAI). Platelet-lymphocyte ratio (PLR), C-reactive protein-lymphocyte ratio (CLR), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and other laboratory data were compared between the two groups within 24-72 hours post-infection. Results: The mild group consisted of 66 cases with an average age of (51. 52±13. 16) years, and the severe group consisted of 14 cases with an average age of (52.64±10.20) years. Disease activity, CRP, platelets, PLR, and CLR were significantly higher in the severe group compared with the mild group (P < 0.05). Univariate analysis using age, disease activity, CRP, platelets, PLR, and CLR as independent variables indicated that disease activity, CRP, PLR, and CLR were correlated with the severity of COVID-19 (P < 0.05). Multivariate logistic regression analysis further confirmed that PLR (OR=1.016, P < 0.05) and CLR (OR=1.504, P < 0.05) were independent risk factors for the severity of COVID-19 in the critically ill patients. Receiver operator characteristic (ROC) curve analysis showed that the area under the curve (AUC) for PLR and CLR was 0.708 (95%CI: 0.588-0.828) and 0.725 (95%CI: 0.578-0.871), respectively. The sensitivity for PLR and CLR was 0.429 and 0.803, respectively, while the highest specificity was 0.714 and 0.758, respectively. The optimal cutoff values for PLR and CLR were 166.214 and 0.870, respectively. Conclusion: PLR and CLR, particularly the latter, may serve as simple and effective indicators for predicting the prognosis of patients with PSS and COVID-19.