SRTM and ASTER GDEM are public DEMs(digital elevation models),which are used widely in terrain analysis.Elevation is the base information for DEM,and slope is one of the most important DEM terrain representation factors.Based on the actual measurement data of elevation and slope,we measured the error of the DEM and slope using the methods of correlation analysis,accuracy analysis,slope spectrum analysis and regression analysis in the Northern Tibet Plateau.The results showed as follows:(1) There was some small errors in the elevation data derived from SRTM and GDEM.The Pearson correlation coefficient between elevation data and the actual measurement is 0.975 and 0.994,the root mean square error(RMSE) 57.381 and 31.106,the accuracy ratio(AR) 2.089 and 1.976,and the relative mean error(R_ME) 1.1% and 0.7%.(2) There is more error with the slope data derived from SRTM than from ASTER GDEM.Compared with the actual measurement,their Pearson correlation coefficient is 0.878 and 0.946,the root mean square error(RMSE) 4.014 and 2.395,the accuracy ratio(AR) 1.238 and 1.034,and the relative mean error(R_ME) 21.5% and 5.5%.(3) The slope spectrum is a new way in terrain analysis,and we found that the accumulative frequency slope spectrum can visually indicate errors in slope derived from DEM.