Abstract: Using the observations from the Jinzhou agricultural ecosystem research station during 2007-2008, the effects of the maize root distribution on land-atmosphere flux exchanges were investigated with the Common Land Model (CoLM). The results showed that there were differences in simulation performance of CoLM for the different annual meteorological conditions, that is, for the case with more precipitation in the growing season of maize in 2008, the simulation accuracies of sensible and latent heat fluxes were higher than that in 2007 with less precipitation. The two parameters, d50 and d95, were used to indicate the shape root distribution profile for 50% and 90% of the total root soil depth, respectively. The simulations of sensible and latent heat fluxes were more sensitive to the former than the latter. The effect of the root distribution on the soil water content (SWC) was increasing with the decreasing SWC and the soil depth within the certain realms and was inappreciable under the condition of extreme drought. In addition, the effects of the root distribution were the most obvious on the simulation of transpiration and next on the simulation of soil evaporation, but ignorable on the simulation of leaf evaporation. On the other hand, it was decreasing on the simulations of sensible and latent heat fluxes with SWC increasing.