Forest biomass is an important content in forest monitoring.It is difficult to precisely measure the tree canopy,which is always considered as a regular shape in the estimation of the volume and surface area of it.For this reason,the aim of this paper to establish standing tree 3D model for the standing tree measurement by through 3D laser scanning technology in Xiaolongshan forest area,Gansu province.The specific method is to get forest inventory factors,such as tree crown volume,surface area at first,and then through biomass model which has brought in tree crown factor to build a biomass model including crown volume and surface area.At last,Combined with the traditional forestry survey data to study different forest stands in Xiaolongshan.The results show that the volume and surface area were calculated using the traditional survey data,and the researches about tree canopy obtained much betterresults; 8 class stand biomass including Quercus alienavar acuteserrata,Pinus tabulaeformis,Quercus variabilis,Betula albo-sinensis,Larix leptolepis,Pinus armandii,Picea asperata and other hard broadleaved mixed forest are6.0507、58.4695、79.8861、64.1154、54.3675、62.2105、90.3241、92.3567t/hm2 respectively.Through nonlinear regression method and tree crown volume regression equation,we get the correlation coefficient is about 0.99.After test,the biomass model established obtains ideal results and it will have practical value on monitoring global change biomass.