The spatial distribution and multi-year change in land surface temperature(LST)over the Qinghai-Tibet Plateau(QTP)was analyzed using MODIS LST products.Firstly,the null pixels were reconstructed by integrating temporal and spatial information.The validity ratio of LST was showed to be over 97%after reconstruction.Secondly,a sine and linear piecewise function was utilized to fit the four instantaneous observations to mean daily LST.Ground observation of 0 cm soil temperature was employed to validate the fitting results,which the accuracy is within 1K.Lastly,a cosine function model was built to describe the seasonal fluctuation of LST.The mean annual LST,the amplitude and the peak LST date were subsequently extracted by this model.Results showed that the mean annul LST was highly correlated to attitude, latitude and the type of underlying surface.Amplitude of LST was showed to rise from the southeast to northwest.The peak date of water was obviously delayed compared with other land cover types.Slope analysis showed that the mean annual LST over the QTP was increasing with a velocity of 0.015Kper year.Amplitude was elevated by 0.076Kper year,which indicated that the probability of extreme weather was larger than before,due to the greenhouse effect and climate change.The peak date of LST appeared earlier to some extent.