This study investigated quantitative forest stand parameters at the plot level such as the tree height,diameter,basal area,and other parameters with terrest riallaser scanning and multi-stop scanning method,then the spatial structural characteristics of one plot level st and of Quer cus var i abil i s f orests in Xishan Mountain of Beijing City were described by using mingling degree,neighborhood comparison and uniform angle index.The result showed that there were fiften populations in arbor layer of Quercus variabil is forests,among which,Quercus variabil is had the obvious advantage in population density and basal area,being the dominant and constructive species of the tree layer.The average mingling degree of the whole stand was 0.306,suggesting the low mingling degree of the stand.The dominant species such as Quercus variabilis and Koel reuteriapani culata population were mainly none or less-mixed,while the accompany ing species generally presented moderate,intensity and high intensity.In the spatial structural units,Quercus variabilis,A certruncatum,Robinia pseudoacacia and Quercus liaotungensis Koidz were mainly of do minant,sub-dominant,and intermediate trees,accounting for 64%,68%,64% and 59% of the total plants of the populations respectively,while the advantage of other populations was not obvious.The uniform angle index value of Quercus variabilis forests was 0.528,indicating that the spatial pattern of the stands was of aggregative distribution,but the aggregation degree was not high and the aggregation scale was not large.