Abstract: Quality of data(2008-2009) from deformation networks of the tenth five-year project in Shaanxi Province are evaluated.Results show that the data are of comparatively high quality.Integrity rate of data in 2009 is as high as 99.43%, and precision for 14 of the 15 observation items of the deformation networks is attained to excellence.Therefore the data could consequently be applied to earthquake forecasting and prediction and relevant researches.Some improving suggestions on data quality are proposed accordingly.