Abstract： Objective:To explore the related factors of negative conversion time (NCT) of nucleic acid in children with COVID-19.Methods:A retrospective cohort study was conducted. A total of 225 children who were diagnosed with COVID-19 and admitted to Changxing Branch of Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from April 3 rd to May 31 st 2022 were enrolled in the study. The infection age, gender, viral load, basic disease, clinical symptoms and information of accompanying caregivers were retrospectively analyzed. According to age, the children were divided into<3 years of age group and 3-<18 years of age group. According to the viral nucleic acid test results, the children were divided into positive accompanying caregiver group and negative accompanying caregiver group. Comparisons between groups were performed using Mann-Whitney U test or Chi-square test. Multivariate Logistic regression analysis was used to analyze the related factors of NCT of nucleic acid in children with COVID-19. Results:Among the 225 patients (120 boys and 105 girls) of age 2.8 (1.3, 6.2) years, 119 children <3 years and 106 children 3-<18 years of age, 19 cases were diagnosed with moderate COVID-19, and the other 206 cases were diagnosed with mild COVID-19. There were 141 patients in the positive accompanying caregiver group and 84 patients in the negative accompanying caregiver group.Patients 3-<18 years of age had a shorter NCT (5 (3, 7) vs.7 (4, 9) d, Z=-4.17, P<0.001) compared with patients <3 years of age. Patients in the negative accompanying caregiver group had a shorter NCT (5 (3, 7) vs.6 (4, 9) d, Z=-2.89, P=0.004) compared with patients in the positive accompanying caregiver group. Multivariate Logistic regression analysis showed that anorexia was associated with NCT of nucleic acid ( OR=3.74, 95%CI 1.69-8.31, P=0.001). Conclusion:Accompanying caregiver with positive nucleic acid test may prolong NCT of nucleic acid, and decreased appetite may be associated with prolonged NCT of nucleic acid in children with COVID-19.