Abstract: Based on the observational data of the eddy-covariance system from Dali national climate observatory in 2011,the main approaches to data processing and quality assessment recently have been selected to preprocess the orignal turbulent data and the influence on calculating turbulent flux at each processing step has been quantitatively analyzed.Meanwhile,the distribution of data quality has been analyzed on a basis of the turbulent steady state test and turbulent flux-variance similarity test,and the flux spatial representativeness of eddy-covariance system has been analyzed on a basis of analytical footprint model.The results showed that the best averaging period to calculate turbulent flux was about 30 minutes in Dali.Spike elimination,double coordinate rotation,sonic temperature correction,time-lag correction,frequency response correction and WPL correction had impact of varying degrees on calculating turbulent flux,especially on the effect of double coordinating rotation on calculating momentum flux and WPL correction on calculating carbon dioxide flux were evident.The turbulent steady state test and turbulent flux-variance similarity test revealed that overall quality of the eddy-covariance data from Dali national climate observatory was good,and the percentage of high quality data for the momentum flux,sensible heat flux,latent heat flux and carbon dioxide flux was 59.4 %,64.2 %,63.8 % and 63.2 % respectively.Footprint analysis showed that the source areas for the eddy-covariance system was in the direction from northwest to southeast and the main contribution source area was southeast area observed from the observation tower.