Tamarix ramosissima community is facing a serious degradation at southern fringe of the Taklimakan Desert.Deficient water conditions impose restrictions on seedlings establishment and survival of T.ramosissima.In order to study root biomass accumulation and spatial distribution of T.ramosissima seedlings to provide suggestions for rehabilitating degraded ecosystem,we set up three irrigation treatments:treatment A (no irrigation),treatment B (moderate irrigation) and treatment C (sufficient irrigation) at southern fringe of the Taklimakan Desert.Result showed that:(1)Irrigation significantly affected root growth and spatial distribution.The root biomass accumulation increased gradually with increased irrigation and the biggest growth rate at the end of growth season (October).Meanwhile the proportion of fine roots also increased from 20.5% to 29.8%,which improved the ability of absorbing moisture and nutrient from soil significantly.(2)Under drought stress (treatment A),the root length of seedlings was the longest,while the horizontal distribution of root was restricted.Under moderate irrigation (treatment B),the root biomass was more than that of treatment A but less than that of treatment C;the root level distribution of T.ramosissima seedlings:treatment AT.ramosissima root depth was shallow,but level distributing of root was most expander in order to use the shallow soil resources more effectively.(3)The most roots are distributed between 0～40 cm of the soil and the wetter,the centralized trend is more obvious.Root biomass was decreasing with the increase of soil depth,so had the same change of root length density of fine roots,but the change of specific root length of fine roots was unconspicuous which could be related with microcosmic environment of soil.The results showed that irrigation had a significant impact on root growth and distribution of T.ramosissima seedlings.Under treatment C(sufficient irrigation),the weight of root biomass is the biggest and spatial-temporal distribution is the largest compare with the others,which indicated treatment C(sufficient irrigation) is conductive to root normal growth and reasonable distribution of T.ramosissima seedlings.