Vegetation greenness and leaf area index (LAI) are two of the most important vegetation phonological parameters. Greenness strongly affects the moisture availability, which regulates the partitioning of solar radiant energy into sensible and latent heat fluxes. LAI is an important factor of stomatal resistance, which controls the plant transpiration. Most of Land Surface Schemes (LSS) use seasonal or constant greenness and LAI while their interannual variability is ignored. In this study, several 10-year simulations of the NCEP Noah LSM have been carried out to investigate the impact of the seasonal cycle and the interannual variations of vegetation on the simulation of surface fluxes and state variables. These experiments have the same configuration as GSWP-2 baseline run but use different greenness and LAI. It is found that LAI has less impact on surface sensible and latent heat fluxes than greenness though the former has larger interannual variability .