Abstract: Seven years (20032009) ecosystem-level monitoring data was collected to examine how seasonal and inter-annual soil water deficit affect the canopy leaf phenology in a tropical rainforest of Xishuangbanna,China.This study found that: there is distinctive seasonal pattern of canopy leaf phenology in the studied forest. Intensive leaf shedding occurred in the latter dry season when peaked in soil water deficit and evaporation demand. Moreover,leaf-shedding mainly occurred in canopies higher than 20 m.There was no obvious intensive leaf-shedding in canopy between 5 and 20 m during dry season.A close positive relationship was found between leaf-shedding amount and cumulative soil water deficit at inter-annul scale. Leaf-shedding amount was higher in the dry year.A cost-benefit analysis indicated that shedding leaves during the driest period was a good way for canopy carbon gain.Therefore,the leaf shedding was regarded as an adaptive strategy for water deficit in Xishuangbanna tropical rainforest.