Abstract: Eddy covariance technology is one of the most powerful tools for research about water and carbon exchange in extremely arid region. The eddy covariance data normally need to be regulated based on the actual situation of the study area for application. Some of the regulations are selecting the suitable sampling and calculation parameters such as sampling frequency and averaging period. In this paper，the impact of averaging period on eddy flux calculation in desert riparian forest has been analyzed. The methodology that the research has adopted was recalculating the latent heat flux（LE），sensible heat flux （H），and CO₂ fluxes（FC） in different averaging period （1~120 min），cooperating and analyzing the calculations of flux values in different averaging periods and 30 min averaging period，and revealing the influences of the averaging period on the calculation of fluxes in the research area，based on the original data（sampling frequency was 10 Hz）from Sep 22 to Oct 17. And the Ogive function is applied to determine the low-frequency contribution to eddy fluxes. The results showed as follows：（1）the changing trend of diurnal mean fluxes and diurnal mean energy balance closure rates（EBR）of 17 researching days were different in different length of averaging period. When the averaging period was shorter than 120 min，both values increased as the averaging period rising；when the averaging period was longer than 120 min，both values decreased substantially as the averaging period rising. And when the averaging period was changing from 15 to 60 min，the two values varied slightly，just about 2%. （2）LE, H and FC flux values had a different degree of variation when the averaging period is longer than 60 min．With further analysis on the forenoon EBR of the 5 samples with similar EBR，it is found that either the averaging period was longer than 60 min or shorter than 15 min，the changes of EBR between the sampling days were much larger than those under other averaging periods. Our research showed that the averaging period 60 min was able to promote the energy balance closure，while 15 min was able to gain more information in this region. （3）The Ogive function showed the similar results that the optimal averaging period should be within the period from 15 to 60 min. The influences of averaging period（15-60 min）were also analyzed on the calculation of hourly eddy fluxes. The results showed that the flux densities were further increased as the averaging period extending when the flux was an upward trend，while the flux densities were further decreased with the averaging period extending when the flux was an downward trend. The innovation point of this article is to evaluate eddy covariance data quality in the extremely arid region in the Tarim Basin. According to this analysis，an averaging period that captures the low-frequency transport may improve the energy balance problem.

Key words: extremely arid region, desert riparian vegetation, Eddy covariance, averaging period, energy balance closure