Using data from the 2000 and 2010 wave of Sample Survey of the Aged Population in Urban/Rural China, this paper analyzes trends and correlates of religiosity among Chinese elderly over 2000-2010 by performing period and cohort comparison and multiple logistic regression, in order to provide further evidence for aging policies in China. Results show that the proportion of elderly having religiosity declined from 15.56% in 2000 to 13.89% in 2010; and this proportion of religiosity among the elderly was decreasing in the same age group over time, and decreasing with age in the same birth cohort, which is consistent with the prediction of secularization theory. Gender, ethnicity, education, party membership/cadre status, chronic disease, self-rated filial piety, living with children, and participations in social organization have significant impact on religiosity among the Chinese elderly.