Over the past several decades, the proportion of older adults in the Chinese population has steadily increased during a period of substantial social change; the effect of these changes on older adults warrants examination. The present study explored changes in subjective well-being (SWB) in older adults by birth cohort and the social factors influential in these changes. We performed a cross-temporal meta-analysis using data from 20,713 adults over 60 years of age; data were obtained from 61 studies that used the Memorial University of Newfoundland Scale of Happiness. The dynamics of SWB in older adults were evaluated as a function of time. The mean SWB score decreased by 4.98 over the measured period, indicating a decrease of .52 standard deviations between 1990 and 2010. In addition, SWB in older adults was significantly correlated with high social connectedness and low overall threat. Specifically, urbanization level, Gini coefficient, personal medical expenditure, and birth rate were strong predictors of SWB. Our research demonstrates that social connectedness and overall threat contribute to SWB in Chinese older adults. As SWB is significantly related to the mental and physical health of older adults, the present study may serve as a useful reference for health care agencies and policy-makers.