With the rapid increasing of the elderly population, how to better meet the long-term care needs of the elderly is becoming an increasingly important social issue. Based on the CLHLS continuous tracking survey data from 2014 to 2018, this article uses SFA to test empirically the influencing factors of informal care for the elderly under the benchmark model, and estimates the impact of income inequality on informal care of the elderly. The results show that the logarithm of family income, financial support provided by pensions or children, widowhood, disability, etc., significantly affect positively the benchmark amount of informal care for the elderly, while the provision of health education in the community significantly reduces the baseline amount of informal care. In terms of specific effects, the overall impact of income inequality reached 76.86%, of which the positive spillover effect of income inequality contributed to 88.66%. In terms of the unilateral effect of the degree of influence, the positive spillover effect of income inequality is as high as 58.12%, the negative crowding-out effect is 33.33%, and the net effect is 24.79%. Group heterogeneity under gender and regional characteristics is small, but with the increase in disability, the net effect of income inequality shows a downward trend. Therefore, based on the income inequality formation mechanism, and with the guidance of improving the care for the elderly, it proposes policy recommendations such as reducing income inequality, optimizing the supply of formal care resources, and strengthening institutional guarantees.