Nine Light Detection And Ranging（LiDAR） metrics were calculated and classified into three classes:canopy height

structural complexity

and cover metrics.Combined with a huge amount of field-measured structural data and estimated age data for individual trees

canopy height and structural complexity metrics were used to analyze the vertical distribution of forest canopy at both plot and regional levels.Picea crassifolia in the study area was primarily half-mature and mature stands; the complexity of the canopy vertical distribution and the differentiation grade of canopy height were low.The canopy cover metrics had a good c orrelation with the field-measured effective Plant Area Index（PAI e） according to the regression analysis（R2= 0.66）.The PAI e of the entire study area was retrieved based on the radiative transfer model and validated by field data.The retrieved PAI e was slightly higher than the field data（R2= 0.67）

and the average absolute error was 0.65.These results show the potential of LiDAR in retrieving forest structure information.