Objective In China,few studies reported the disability situation and the association between disabilities with chronic conditions in aged people.This study investigates the cross-sectional trends of prevalence and severity of activities of daily living disability(ADL)in Chinese oldest-old people from 1998 to 2008,and identified the potential risk factors of disability.Design A combination of population-based longitudinal prospective study and probabilistically sampling cross-sectional studies.Setting The Chinese Longitudinal Healthy Longevity Survey (CLHLS)was based on a random sampling of aged people from twenty-two provinces in China.Particioants A total of 52,667 participants aged from 80 years old to 105 years old sampled in the year of 1998(n=8,768),2000(n=10,940),2002(n=10,905),2005(n=10,396)and 2008(n=11,658)were analyzed respectively.Results The prevalence of ADL disability decreased from the year of 1998(18%)to 2008(12%).The disability prevalence significantly increased in 2002 and decreased in 2008(P<0.001)in total participants than the year of 1998.The prevalence trends of low ADL disability level were almost identical with that of the total ADL disability.Stroke/cerebrovascular disease(CVD)and cognitive impairment were the strongest risk factors of disability.Vision impairment became less associated with ADL disability(P=0.045),while the association between multimorbidity and ADL disability became stronger(P=0.033).Conclutions:The prevalence of ADL disability declined among the oldest-old population in China from the year of 1998 to 2008 without obeying a linear pattern.Temporal trends of ADL disability mainly attributed to the change of low disability level prevalence.Stroke/CVD and cognitive impairment were the most common risk factors of disability.Vision impairment caused disability has become less common,while risks of multimorbidity related disability increased.