Objective:To analyze the incidence and related factors of parenteral nutrition(PN)-associated cholestasis(PNAC)in extremely low birth weight infants.Methods:The clinical data of 305 extremely low birth weight infants who were received PN sup-portive treatment were collected retrospectively.The incidence of PNAC was calculated.Infants included were divided into the observa-tion group(with PNAC,n=54)and the control group(without PNAC,n=251).Information of the infants was collected,including gender,gestational age,delivery mode,birth weight,1 min and 5 min Apgar scores,complications(neonatal infection,neonatal anemia,etc.),length of hospital stay,feeding difficulties,PN start time,PN duration,cumulative dosage of amino acids,cumulative dosage of fat emulsion,and the levels of serum indicators[alanine aminotransferase(ALT),aspartate aminotransferase(AST),total bilirubin(TBil)and total bile acid(TBA)]on 14 day after birth.Univariate analysis and multivariate analysis were conducted to screen the factors influencing the occurrence of PNAC in extremely low birth weight infants.Results:There were 54 cases of PNAC,with an inci-dence rate of 17.70％.Compared with the control group,gestational age and birth weight of the observation group were lower(P＜0.05).The proportion of neonatal infections,length of hospital stay,the proportion of feeding difficulties,PN duration,and the levels of ALT,AST,TBil and TBA in the observation group were higher and longer(P＜0.05).Logistic regression analysis showed that high birth weight was a protective factor,while PN duration and the levels of ALT,AST,TBil and TBA were independent risk factors for PNAC in extremely low birth weight infants(P＜0.05).Conclusion:Birth weight,PN duration and the levels of ALT,AST,TBil and TBA are helpful for evaluating and predicting the occurrence of PNAC in extremely low birth weight infants.