高程是数字高程模型(DEM)的基本信息，坡度是DEM进行地形分析的重要描述性因子之一。选取藏北高原区为研究区域，在实测GPS高程值和实测坡度数据的基础上，对SRTM与ASTER GDEM高程值和提取的坡度进行了误差分析。研究表明:(1)SRTM和ASTER GDEM在采集高程值时误差较小，二者与实测值之间的Pearson相关系数分别为0.975和0.994，中误差(RMSE)为57.381和31.106，精度比率(AR)为2.089和1.976，相对平均误差(R_ME)为1.1%和0.7%；(2)SRTM提取坡度的误差较大，而ASTER GDEM提取的坡度误差较小，二者与实测值之间的Pearson相关系数分别为0.878和0.946，中误差(RMSE)为4.014和2.395，精度比率(AR)为1.238和1.034，相对平均误差(R_ME)为21.5%和5.5%；(3)频率累计坡谱能直观地表现DEM提取坡度的误差大小。

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.