Abstract: A micrometeorological model was developed to simulate momentum,heat and water vapor transfer within and above forests.Simple Biosphere Model (SiB) was also used for providing such parameters as the evapotranspiration rate of the vegetations.In processing dispersive transport term in momentum equation.first order closure scheme by Li (1985) was used after modification according to analysis of physical processes.After that,the modified method was also used for calculating various dispersive terms which appeared in the other equations.The vegetation canopy was devided into several layers according to the leaf area density.The evapotranspiration rate of vegetation and its latent heat were considered in water vapor conservative equation and heat equation respectively.Absorbed net radiations by different layers were different within the canopy because of various leaf area density.