To separate and purify Caulis Dendrobii Officinalis polysaccharides(DOP) to obtain DOP-1 and to study the anti-aging effect of DOP-1 with Caenorhabditis elegans.Methods:Fresh Caulis Dendrobii Officinalis was extracted and the extract was concentrated，followed by ethanol precipitation and vacuum drying to yield crude DOP.Crude DOP was separated on DEAE-Sepharose Fast Flow column and eluted with HW-55F gel column to result in the pure DOP-1.Parameters such as purity and relative molecular weight were determined by high-performance gel-permeation chromatography.Moreover，the effect of different concentration of DOP-1(100 μg/mL，200 μg/mL，400 μg/mL) on lifespan，reproductive ability，and lipofuscin accumulation of C.elegans，and the resistance of C.elegans to high temperature and oxidative stress was investigated.Results:The isolated and purified DOP-1 was a homogeneous polysaccharide with relative molecular weight of 3.260 × 105 Da.Different concentration of DOP-1 could significantly prolong the lifespan of C.elegans(P<0.05 or P<0.01)，particularly the 200 μg/mL DOP-1 which increased the lifespan by 43.37% compared with the control group.DOP-1 can protect C.elegans from high temperature injury and oxidative stress injury and effectively reduce the accumulation of lipofuscins.However，it has no remarkable influence on the reproductive ability of the C.elegans.Conclusion:The isolated and purified DOP-1 is a homogenous polysaccharide with significant anti-aging effect，which can serve as a reference for the research on the relationship between its structure and anti-aging activity.