Objective: Recognizing vulnerable groups of catastrophic health expenditure and reducing the risk of catastrophic health expenditure. Methods: Data were drawn from the 2018 wave of China Health and Retirement Longitudinal Study. Chi square test was used to compare the incidence of catastrophic health expenditure between different groups. Logistic regression analysis was used to determine the influencing factors of catastrophic health expenditure. Results: The incidence of catastrophic health expenditure of families included in this study was 27.37% in 2018. Logistic regression model showed that married, poor self-rated health, small household size, poor household economic situation, household with member used outpatient or inpatient health services, household with member with chronic diseases and household with member over 60 years old were vulnerable groups of the occurrence of catastrophic health expenditure. Conclusion: Given the high incidence of catastrophic health expenditure, more precise and effective strategies are needed to reduce the risk of catastrophic health expenditure.