The annual assimilating shoots of 6 Haloxylon ammodendron species were selected as experimental materials,which were gotten from arid region of northwest China according to precipitation gradient which is from east to west.9 anatomical structures were measured.We analyzed the relationship between anatomical differences and ecological factors of the assimilating shoots of H.ammodendron,to provide theoretical basis for the protection and utilization of the ecological environment and H.ammodendron resources in arid areas of China.Results showed that:(1)the anatomical structure of the assimilating shoots of H.ammodendron in the arid desert environment with continuous wreath of palisade tissue,structure,crystal cell and water storage organization structure,but the epidermis cells,cutin layer thickness,hole position under the gas chamber difference with xerophyte structure,mainly displays in the epidermal cells and corneous layer is thinner,porosity nuder half wubsidence and gas chamber is not developed.(2)9 anatomical structures of the assimilating shoots of each characteristic of 6 H.ammodendron species have significant differences by variance analysis.The variability coefficients are greater in the number of vascular bundle and cuticle thickness with the values of 22.78% and 15.20%,respectively;Correlation analysis showed that each index has different degree of correlation with eight ecological factors,which are longitude,latitude,altitude,average temperature in January and July,annual average temperature,annual precipitation and annual average relative humidity.The diameter of assimilating shoots thickness,palisade cell cut to length,water storage tissue thickness and vascular cylinder diameter have different degrees of correlation with eight ecological factors.(3)6 populations of H.ammodendron could be divided into 2 categories by cluster analysis.The results of cluster analysis were identical with the habitat types and geographical distribution of H.ammodendron;as fewer natural rainfall from east to west,the drought resistance of H.ammodendron gradually strengthened.