Objective To investigate the factors influencing the length of hospital stay for secondary cholangitis following hepaticojejunostomy in infants with biliary atresia, and further analyze the determinants of treatment complexity, with the aim of improving doctor-patient communication quality. Methods A retrospective analysis was conducted on infants with cholangitis after Kasai Hepatoportoenterostomy admitted to West China Second University Hospital from May 1, 2018, to April 30, 2024. The patients were divided into two groups based on the length of hospital stay: ≤4 days group (65 cases) and >14 days group (59% cases). Differences in demographic characteristics, clinical features, laboratory indicators, and imaging examination results between the two groups were compared. Variables with statistically significant differences between the groups were subjected to multivariate regression analysis.Results A total of 124 infants with cholangitis after Kasai Hepatoportoenterostomy were included in this study, with 54 males (43.5%) and 70 females (56.5%). The age at admission was 143.5 (105.0, 263.3) days, and the length of hospital stay was 14 (10, 20) days. Statistically significant differences were observed in the following variables: days of fever after admission (U=834, P<0.001), age at admission (U=1 408.5, P=0.011), postoperative days (U=1 308, P=0.005), virological testing (χ2 =6.047, P=0.014), bacteriological testing (χ2=8.446, P=0.004), platelet count (PLT) (U=1 303, P=0.026), total bilirubin (TB) (U=930, P<0.001), direct bilirubin (DB) (U=941.5, P<0.001), indirect bilirubin (IB) (U=944.5, P<0.001), total bile acid (TBA) (U=874, P=0.029), and adenosine deaminase (ADA) (U=801.5, P=0.022).Conclusion The younger the age at admission, the shorter days after surgery, and the more days of fever after admission, the longer the length of hospital stay for the infants. The length of hospital stay is correlated with etiological infections, particularly more closely with bacterial infections