The family plays a major role in medical decision-making in China. Little is known about whether family caregivers understand patients' preference for receiving life-sustaining treatments and are able to make decisions consistent with them when patients are incapable of making medical decisions. We aimed to compare preferences and attitudes concerning life-sustaining treatments of community-dwelling patients with chronic conditions and their family caregivers. We conducted a cross-sectional study among 150 dyads of community-dwelling patients with chronic conditions and their family caregivers from four communities in Zhengzhou. We measured preferences for life-sustaining treatments (cardiopulmonary resuscitation, mechanical ventilation, tube feeding, hemodialysis, chemotherapy), who should decide, the timing of making decisions, and their most important consideration. The consistency of preferences for life-sustaining treatments between patients and family caregivers was poor to fair, with kappa values ranging from 0.071 for mechanical ventilation to 0.241 for chemotherapy. Family caregivers more frequently preferred each life-sustaining treatment for the patients than the patients themselves. More family caregivers than patients preferred the patient to make their own decisions about life-sustaining treatments (29% of patients and 44% of family caregivers). The most important considerations when deciding on life-sustaining treatments are family burden and the patient's comfort and state of consciousness. There is a poor to fair consistency between community-dwelling older patients and their family caregivers in their preferences and attitudes towards life-sustaining treatments. A minority of patients and family caregivers preferred that patients make their own medical decisions. We recommend healthcare professionals to encourage discussions between patients and their families on future care to improve the mutual understanding within the family about medical decision-making.