Desert Populus euphraticu forest widely distributes in an arid desert region(30°-50°N),its dominated species are Salicaceae and Tamaricaceae. The typical P.euphraticu forest exists in Tarim River Basin, also occupys over 350,000 km2 and 90% of total P.euphraticu area in china. The existence and development of desert P.euphraticu has great ecological, economical and social benefits, and controls the structure、function and sustainable development of Tarim desert ecosystem. Since 1960s soil and water resources of upper and middle reaches of the Tarim River were excessively exploited, which induced to recession, nonbearing trees and death of large area P.euphraticu forest, and directly damaged sustainable development of oasis agriculture and ecological balance. This objective of this study was to illuminate the population structure and quantitative dynamic, living status and development trend in the future, and provides theoretical base for utilizing resources rationally and protecting dominant population. The original desert forest and the center zone are located in Nature Reserve Region of Awati and Luntai county in upper and middle reaches of Tarim River, the environmental conditions of Awati county are good and the groundwater level is shallow, P.euphraticu grows well. On the contrary, Luntai county has extremely poor conditions for P.euphraticu growth. The research plots were selected in Awati(80°25′E,39°40′N) and Luntai (84°15′E,41°09′N)county. The 1.2hm2 plot was investigated in 2005, and was divided into 480 subplots. All the trees whose stems are over 2.5 cm in DBH were identified, measured, tagged, and mapped.The time-specific life table was created for species, and the survivorship curve, size and age structure were analyzed with field data in this paper. The results showed the size and age structure characteristics of different P.euphraticu population were obviously different in the two study sites.The size and age structure of P.euphraticu population in Awati county showed positive pyramidal type, indicating that it had rich saplings banks and regenerated well, it is progressive population. The expected average life of middle age trees was high, and the survivorship curve of the population conformed to the type of Deevey III. The size and age structure of P.euphraticu population in Luntai county showed approximate normal distribution, it had a lot of sprout seedlings and grew feeble. It indicated that population kept stability currently. The expected average life decreased with age increasing, and the survivorship curve of the population conformed to the type of Deevey II. The Killing power and mortality rate curve of two different populations had obviously different. There were two peaks of mortality rate and killing power of Awtai county population in the lifespan, one was from seedlings to young trees(0-20 years)and the other in the adult stage(80-100 years). It was supposed to result from the inter-and intra-specific competition. In Luntai county, one peak was middle age stage(100-120 years), and the other in the old stage(160-180 years). It was supposed to result from deteriorative habitat and physiological decline. It is suggested that quantitative dynamics of population is impacted by environmental factors and biological characteristic of P.euphraticu