In this research we use UAV stereo imagery to extract Digital Surface Model( DSM) of the study area which is located in the mountain areas of southwest Fengning county,Hebei province. Calibration points were set at bare ground through the imagery manual interpretation,followed by the elevation calibration of DSM using parameters fitted by the values of DSM and DEM at the corresponding calibration points. Then the forest height was extracted and averaged over each forest stand segment combining with forest s...