定义了东亚海陆热力差指数 ( ILSTD) ,讨论了它与东亚夏季风的强弱年际变化及夏季降水的关系。结果表明 :该海陆热力差指数较好地反映了我国东部季风区夏季降水的年际异常变化 ,强海陆热力差指数年 ,华北地区降水偏多 ,长江、淮河流域明显干旱 ;弱海陆热力差指数年 ,长江、淮河流域降水又异常偏多。ILSTD的异常变化对影响我国东部季风区降水的大气环流型具有较强的识别力 ,尤其是对夏季西太平洋副热带高压的位置与强度的识别。强弱指数年 ,北半球 5 0 0 h Pa上东亚夏季风环流系统各成员及高低纬环流系统的相互配置和强度变化可以较合理地解释夏季风的强弱变化和东部季风区夏季降水的异常变化特征。 The East Asian sea-land thermal difference index (ILSTD) is defined, and its relationship with the intensity of the East Asian summer monsoon and the summer precipitation are discussed. The results show that the difference between the sea-land thermal exponents reflects the interannual anomalous change of the summer monsoon rainfall in eastern China. The strong index of the difference in the thermal-land-sea thermal exponents shows that the precipitation in North China is higher than that in the Yangtze River and Huaihe River valleys, In the year, the precipitation in the Yangtze River and Huaihe River was anomalous. The abnormal variation of ILSTD has strong recognition on the general circulation pattern affecting the precipitation in the monsoon region of eastern China, especially the recognition of the position and intensity of the western Pacific subtropical high in summer. In the strong and weak index years, the mutual disposition and intensity change of members of the East Asian monsoon circulation system and the latitudinal and longitudinal circulation systems in the northern hemisphere at 500 hPa can explain the changes of the intensity of the summer monsoon and the abnormal changes of summer monsoon in the eastern monsoon region more rationally feature.