【Objective】Global ecosystem dynamics investigation (GEDI) multibeam lidar and ice, cloud and land elevation satellite-2 (ICESat-2) photon clouds use different lidar technologies, resulting in differences in tree height extraction values between the two tasks. The purpose of this study is to compare the ability of two spaceborne lidar data to effectively invert forest height under different conditions. 【Method】By locating and filtering the GEDI L2A field information, and verifying the terrain elevation accuracy, the tree height of six algorithm groups was compared. The ICESat-2 data was denoised, a photonic cloud classification algorithm based on slope change was proposed, the ground photon line and the canopy top line inversion forest height were established, and the accuracy of GEDI and ICESat-2 in the study area was verified and compared by using the measured data and airborne lidar data. Finally, the differences of GEDI and ICESat-2 data in different terrain slopes, vegetation coverage and forest types were quantitatively analyzed. 【Result】According to the GEDI L2A product data, by comparing the optimal algorithms in GEDI L2A algorithm group from a1 to a6, the inversion accuracy of a4 was better: R²=0.94, root mean square error was 2.31 m, and mean absolute error was 1.27 m. For ICESat-2 data, R²=0.81, the root mean square error was 3.68 m, and the mean absolute error was 2.45 m, calculated using a 50 m window. Vegetation coverage had a greater impact on the tree height of the two spaceborne lidars compared to the terrain slope and forest type. 【Conclusion】Compared with ICESat-2 data, GEDI data showed a better evaluation accuracy standard for the more gentle and densely populated areas with coniferous forest types.