Abstract: Surface energy fluxes play a significant role in land-air interaction. To quantify the influence of resistance coefficients on surface energy fluxes in the Simple Biosphere Model (SiB₂), the sensitivities of sensible heat flux (H) and latent heat flux (LE) to resistance coefficients are examined by using the one-factor-at-a-time method and fractional factorial analysis method. The results show that, i) H is more sensitive to C₂ (called ground to canopy air-space resistance coefficient) while LE is more sensitive to C₁ (named bulk canopy boundary-layer resistance coefficient);ii) H increases with increasing C₁ and decreases with increasing C₂, while LE always decreases with increasing C₁ or increasing C₂;and iii) the sensitivities of both H and LE decrease with increasing coefficients and their relative sensitivities increase with increasing coefficients. Furthermore, the reasonable explanation about the sensitivity of H and LE are given considering the distribution of land cover and vegetation in Nagqu.