Abstract: Animacy provides important lexical semantic cues for relative clause processing.Yet individuals' ability to use animacy cues may change with advancing age.In this study, comparison was made between younger and older adults in animacy effect on relative clause processing through a self-paced reading task.Mandarin relative clauses were used as the experimental materials and the animacy of RC objects(animate, inanimate) and main clause subjects(animate, inanimate) were manipulated.The results suggest that for older adults, the animacy of RC objects and main clause subjects had no significant effect on the reading times in online processing.For younger adults, the relative clauses with inanimate main clause subjects were more difficult to process than those with animate main subjects.The finding indicates that there is an age-related decline in the ability to utilize animacy cues in sentence processing.The findings supported the Capacity Constrained Comprehension Theory.