By cooperating the multiple back propagation(BP) networks together,the higher layer neural network propagates conversely the output deviation until to the lower layer neural networks to amend the network weights and based on which,item recommendation is accomplished in the forward process of two layers networks relying on the factors such as ratings,etc.

Based on principle of cost- benefit analysis and in combination of micro economic theory and characteristics of environment projects, this paper introduces specific application of economic evaluation to environment project by way of establishing model of quantitative cost effective evaluation for the purpose of economic analysis and evaluation of environment project.