Make natural forest birch at Da Qingshan nature reserves in Inner Mongolia as the research object. The data is from the National Second-Class investigation data in 2006 by Inner Mongolia survey and design institute of forestry in 2006. Take 8 forest centre as study areas. All these datas would be sifted, and chosen the datas which the varieties of trees is white birch and the formation of the tree species is pure forest classes. The total of data is 4785. Use of Matlab software log-the sigmoid type function (logsig) and linear function (purelin) for the role of neurons. Based on the function of the concept of stand growth model, we choose age requirement (A), status level (N) and crown density (S) as input variables and the forest accumulation per hectare (M) as output variables to build and ttrain the stand growth BP artificial neural network model. And test the model fitting precision and inspection accuracy , the model fitting precision is 99.93%, inspection accuracy is 97.79%, these show that neural network modeling has better fitting precision and adaptability for the stand growth, and has good prediction ability.