Abstract: Using the principles of statistics and analysis method，effects of climatic factors on thousand kernel weight in main development stage of highland barley in Tibet are analysed．The thousand kernel weight-climate model of highland barley is performed．The results from tests show that，from the floweriag to milking stages，ahout 18．2℃ for mean temperature and more radiation are favor of improving thousand kernel weight．but high temperature and partly raining or cold and rainy weather cause thousand kernel weight to be decreased.