Weather and climate in Beijing area may be affected by surface energy partitioning in Beijing suburbs.To evaluate the performance of land surface models in energy partitioning simulation over sparse grasslands in Beijing suburbs,the original and modified versions of Simple Biosphere Model 2(SiB2) are applied to simulate the surface radiation balance,turbulent energy budget,and soil temperature and moisture over a tank exercise field in Beijing suburban area from 22 July to 5 August 2010.Simulated results are compared against the direct measurements.Results show that:1)The modified SiB2 underestimates net radiation by 5.81% when the original SiB2 underestimates net radiation by 11.32%.The modified SiB2 where the soil thermal conductivity is updated can better simulate the soil temperature(including the soil surface temperature) and the upward-wave radiation;2)The modified SiB2 can better simulate the sensible heat and latent heat fluxes,but both the original and modified SiB2 underestimate the soil heat flux.