Objective To explore the factors which influence patients in the illness-caused poverty families in rural to request for discharging from hospital so as to provide evidence for perfecting medical security system. Methods By convenience sampling method, 453 inpatients in the illness-caused poverty families were face-to-face interviewed in Miyi County of Sichuan Province, Binhai County of Jiangsu Province and Xingtai County of Hebei Province. Chi-square test was used to assess the affecting factors of respondents’ own request for discharging from hospital. Results Respondents were more likely to choose higher level hospitals, but 24.8% of them needed financial support or loans and 7.1% of them asked for discharging from hospital. The main factors are medical institutions, age, education, employment, self-rated health, the familial asset per capita and average agrarian area, per capita annual incomes and expenditure, Engel coefficient, the proportion of expenditure on education and health care, hospitalization expenses and payment methods, and belief in doctors. Factors in different regions are different. Conclusion The catastrophic health care system should be established according to regional characteristics. More attention must be paid to the ratio of individual payment in county-level hospitals. The implementation of the system has its definite realistic meaning and anticipated effect on effectively solving “sickness poor” and “poverty due to illness” for vulnerable groups.