Abstract: Zygophyllum loczyi Kanitz， a perennial herb， one species of Zygophyllaceae， is endemic to China. It is distributed in Inner Mongolia，Gansu and Xinjiang Province，and might plays an important role in sustaining the ecological environment in Western China due to its attribute of enduring arid，resistance to salt and wind erosion，adaption to poor soil and to cover of sand. However，little is known about the relativity of Z. loczyi′s reproductive elements，ramet generation and the phenotypic plasticity of allocation of rament at present. So that，the paper is try to quantitatively analyze the law of change of phenotypic plasticity of ramet reproductive element in [Z. loczyi′s] population at seed maturing stage and expect to provide the theoretical basis for allocation strategy of substance and energy in Z. loczyi′s population and the theoretical evidence for conservation，sustainable exploration of biodiversity in semi-arid region. The study site is located at Ili Valley，NW Xinjiang. The valley’s enjoys the dry-desert continental climate. The random large sampling to reproductive ramet at Z. loczyi′s population was taken at its seed maturing stage at late Oct. in 2009. At sampling，the ramet were removed from the horizontal and then separate each other，finally the 30 individual was selected. And then to gradually check the biomass of leaf，pod，straw one by one，the next step is to number the seed in each pod and weight their biomass. The number index is produced by percent ratio of biomass of each ramet to whole biomass of ramet. EXCEL 2003 was used to do data processing and cartography. The results show the biomass of reproductive ramet individual of Z. loczyi at seed maturing stage is 112.21±65.38 g；pod biomass is 12.11±8.69 g and pod number is 149.43±106.24；seed biomass and seed number respectively is 14.25±10.65 g and 3961.97±3063.16； the percentage of reproductive allocationⅠ and Ⅱis 10.78%±4.07% and 13.16%±7.44% respectively. Reproductive allocationⅠ，Ⅱ respectively is conspicuous negative correlation to biomass of leaf and straw. Meanwhile，the above results further reveal the each quantitative character of ramet reproductive element has obvious phenotypic plasticity and some growth regulation strategies appear at individual level in population；the equal ratio and different ratio phenotypic plasticity regulation appear in reproductive ramet of population.

Key words: Zygophyllum L., module, boimass, reproductive allocation, phenol-typic plasticity