A new composite index model is put forward by combining various met-eorological factors,effective source height,emission law and actual popula-tion density.It can overcome various man-made coefficient error.By means of microcomputer software development,the effect of parameters and the heavy and complicated ealculations are solved.By using microcomputer fitti-ng,the actual devotion of pollution sources of waste gas to the pollution of urban atmospheric environment is described quantitatively.A set of methods for predicting atmospheric environmental quality is set up,which has been applied in Changchun City.The theoretical prediction values and the average of measured values over years are expressed as Y=1.556+1.055X(r=0.8925), with a high precision.This achievement may be used in environmental mana-gement,selecting factory location,quantitative management of pollution sou-rces and environmental prediction.