Data of electronic medical records of patients hospitalised in the paediatric department of  Fujian Medical University Union Hospital(FJMUUH) from 21 January 2019 to 20 January 2021 were analysed before and during the COVID-19 pandemic. During the COVID-19 outbreak period, paediatric hospitalisation was reduced by 29.6%, from 1255 to 884. The proportions of infection-related diseases (36.3% (455 cases) vs 20.8% (184 cases)), respiratory system-related diseases (22.5% (283 cases) vs 9.4% (83 cases)); and endocrine, nutritional and metabolic diseases (17.1% (214 cases) vs 9.2% (81 cases)) decreased significantly, whereas that of musculoskeletal and connective tissue diseases increased from 11.0% (138 cases) to 20.1% (178 cases), thereby becoming the most common reason for hospitalisation. The proportions of diseases of the nervous system (12.4% (156 cases) to 18.8% (166 cases)) and mental and behavioural disorders (0.2% (3 cases) to 2.1% (19 cases)) increased significantly. The average length of hospital stay increased after the outbreak (7.57±6.53 vs 8.36±6.87).