Canopy conductance (gs) plays an important role in the terrestrial ecosystem-atmosphere water and carbon dioxide exchanges, and hence simulation of terrestrial ecosystem responses to the future climatic change necessitates reliable parameter of gs.In this study, measurement and simulation of gs over the temperate desert steppe were carried out in Inner Mongolia, China, in the growing seasons from 2008 to 2009, with more dry soil moisture in 2009 than in 2008 for the analysis period.gs was calculated by inverted Pemman-Montaith equation, and regarded as the measured gs.Eddy covariance technology was used to measure the evapotranspiration.Half-hourly gs showed diurnal variation pattern with values gradually increasing until around 9:00, and compared higher and relative calm from 9:00 to 18:00, then gradually decreasing after 18:00.The nighttime gs fluctuated severely.The peak gs of 0.0059 m s-1 occurred in 2008.Averaged gs from9:00 to 18:00 were 0.0010 and 0.0009 m s-1 for 2008 and 2009, respectively.Half-hourly gs responses to environmental factors (e.g.photosynthetic photon flux density, Q; air temperate, T; vapour pressure deficit, D; soil water content, θ; leaf area index, L) were examined, and showing gs response to Q in the Gaussian fashion, to T and D in the exponential decay manner, to θ in the exponential growth manner, to L in linear increase manner.The environmental response functions of gs were different from the previous results.Jarvis model was used to simulate the response of gs to environments, and a modified gs model for the temperate desert steppe could be expressed as following:gs=k0 exp(-0.5(Q-k1/k2)2-k3D-k4T+k5θ)(k6L+k7)where the k0-7 were the fitted parameters.Two circumstances (single-year and integrated-years) were taken accounted to the fitted parameters applicability for different hydrological years.The result suggest that there is not obvious difference in gs simulation performance under two circumstances, and gs could be expressed suitably by just one parameter set for different years.The modified gs model could be effective for half-hourly gs simulation for the temperate desert steppe.