Abstract: Using the principles of statistics and analysis meathod,effects of climatic factors on mature spike number of highland barley in Tibet are analyzed.The mature spike number-climate model of highland barley is performed. The results from tests show that,from three-leaf to tillering stages, more raining are favor of improving mature spike number. From tillering to jointing,the disadvantageous factors for mature spike number are high temperature and partly raining.The temperature and precipitation condition affect mature spike number from jointing to heading.In recent 35 years, climatic warming and rainfall decreasing occurred in tillering to jointing stages,but that are disadvantageous conditions of increasing mature spike number.