BackgroundChina's family doctor contracting service is an important part of deepening the reform of the healthcare systems, aiming to further develop chronic disease management services, enhance the capacity of primary health care services and improve the health of residents. The purpose of this study was to explore the influence of multiple chronic conditions in the elderly on family doctor contracting and whether socioeconomic status played a moderating role.MethodsA cross-sectional survey was conducted in Beijing, China. A total of 1814 elderly people over 60 years old were included in this study using a whole-group sampling method. The univariate analysis and logistic regression analysis was used to analyze the data.Results21.72% of the elderly signed up with family doctors. The multiple chronic conditions was a factor influencing the elderly to sign up with family doctors (OR = 1.44, 95%CI = 1.28–1.61), and the higher the degree of multiple chronic conditions, the stronger willingness to sign up. Socioeconomic status positively moderates the effect of multiple chronic conditions on signing. Also, physical activity intensity (OR = 1.25, 95%CI = 1.03–1.54) and willingness to first visit primary care facilities (OR = 1.38, 95%CI = 1.25–1.54) influenced the elderly to sign up with family doctors.ConclusionsThe elderly with a high degree of multiple chronic conditions, high activity intensity, and a strong willingness to first visit primary care facilities were more likely to sign up with family doctors. The health literacy of the elderly should be further improved, and publicity on the family doctor contracting service policies for the elderly with lower socioeconomic status should be strengthened to guide them to sign up with family doctors. At the same time, the service capacity of primary care facilities should be further improved to meet the health needs of the elderly.