Objective To observe the clinical characteristics of moderate coronavirus disease 2019 (COVID -19) patients infected with Omicron variant BA.2 in Quanzhou City, and analyze risk factors for nucleic acid negative conversion time. Methods Clinical data of 67 moderate COVID -19 patients infected with Omicron variant BA.2 in Quanzhou First Hospital Affiliated to Fujian Medical University from March 13, 2022 to April 5, 2022 were collected, clinical characteristics and influencing factors for nucleic acid negative conversion time were retrospectively analyzed. Results The male to female ratio of the enrolled patients was 1 ∶1.03, the age ranged from 9 to 97 (41.45±17.51) years old, 35.82% of patients had underlying diseases, and 83.58% received COVID -19 vaccine. The most common clinical symptom at the initial diagnosis was cough (62.69%), followed by fever (32.84%). The proportions of decreased white blood cell (WBC) count, increased neutrophil percentage and decreased lymphocyte count were 11.94%, 7.46% and 29.85% respectively, the increased proportions of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatine kinase and creatine kinase isoenzyme were 8.95%, 10.45%, 25.37%, 14.93% and 14.93% respectively, the increased proportions of C-reactive protein (CRP), interleukin-6, erythrocyte sedimentation rate and procalcitonin were 35.82%, 71.64%, 56.72% and 4.48%, respectively; the increased proportions of D-dimer, creatinine and ferritin were 8.95%, 28.36% and 13.43%, respectively, 46.27% of the patients were positive for IgG antibodies. Pulmonary CT mainly showed multiple and scattered lesions in the periphery of both lower lungs, patchy high-density shadow and ground glass shadow were more common, and 1.49% of patients had a small amount of bilateral pleural effusion. 10.45% of the patients had complications, the average time of nucleic acid negative conversion of SARS-CoV-2 was (18.12±5.37) days, the average time of hospitalization was (19.45±5.41) days. None of patients progressed to severe/critical disease, all were cured and discharged from hospital. Respiratory disease and elevated CRP were independent risk factors for prolonged SARS-CoV-2 nucleic acid negative conversion time(all P < 0.05). Conclusion Clinical symptoms of moderate COVID -19 patients infected with Omicron variant BA.2 in Quanzhou City were mild at the initial diagnosis, cough was the most common symptom, and some patients were complicated with underlying diseases, most of them completed COVID -19 vaccination, the prognosis was good after active treatment. SARS-CoV-2 nucleic acid negative conversion time is long, which is significantly related to respiratory diseases and elevated CRP.