Background Age has been identified as a prominent predictor of loneliness, although the findings about the relationship between age and loneliness are inconclusive. This study examines the relationship between age and loneliness in the context of China, with a focus on residential and gender differences. Methods Data were from the Chinese General Social Survey (CGSS) of 2017. A total of 3899 respondents were included. Loneliness was measured using a three-item Short Loneliness Scale. Age, squared terms of age, residential type, gender, and other socio-demographic characteristics were included in the study. Regression analyses were conducted among the total sample and subgroups of different gender and residential type subgroups, to investigate the association between age and loneliness. Results There is a reverse U-shaped tendency between age and loneliness that peaks at the age of 47. This tendency is true of the male subgroup, that peaks at the age of 55, while the female respondents do not share that tendency. The inverted U-shaped distribution holds true for urban but not for rural residents. The female respondents reported a higher level of loneliness than the male. The rural respondents reported higher loneliness than their counterparts. Conclusions This study demonstrates that an inverted U-shaped tendency between age and loneliness existed for the entire group, and the male and urban subgroups. Implications for service and practice are proposed based on the empirical findings.

Due to labor migration and social changes, the Chinese elderly are facing significant social isolation, along with changes in aging attitudes. However, whether social isolation affects loneliness among the Chinese elderly and whether this relationship is moderated and mediated by aging attitudes is unclear. This empirical study aimed to respond to the above questions in the Chinese context, Based on the data from the 2014 China Longitudinal Aging Social Survey (N = 6,645), the results showed that social isolation is a positive predictor of loneliness; aging attitudes mediate the relationship between social isolation and loneliness. Social isolation affects the loneliness of the elderly partially by weakening positive aging attitudes and strengthening negative aging attitudes; aging attitudes moderate the effect of social isolation on loneliness. For those older adults with higher positive aging attitudes, social isolation has a much smaller effect on loneliness. While for those older adults with higher negative aging attitudes, social isolation has a more substantial effect on their feelings of loneliness. Our results indicate that less social isolation is an effective way to relieve loneliness, and maintaining higher positive aging attitudes and lower negative aging attitudes, is important for the Chinese elderly to prevent loneliness when facing social isolation.