Based on the American NASA monthly precipitation grid data, the monthly mean surface temperature anomalies grid data from the CO2 Information Analyses Centre, USA, the NCEP/NCAR reanalysis global grid data and the stations observational soil temperature data from the Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences, the authors study the Asian-African summer monsoon meridional circulation weakening in the mid-1960s on interdecadal time scale and the related global climatic anomalies phenomena. The results show that the tropospheric temperature reduced obviously and the global oceanic temperature abnormal changes in the mid-1960s are mainly characterized by SST increasing in the Indian Ocean and SST decreasing in the northern Pacific Ocean and the northern Atlantic Ocean. Simultaneously, the soil temperatures at 1.6-m and 3.2-m depths in Chinese continent and the surface temperature in the Tibetan Plateau decreased respectively and remarkably in the mid-1960s, which reduces the thermal contrast between Asian continent and the Indian Ocean. Accordingly, the easterly jet weakened, finally the Asian-African summer monsoon weakened too and the monsoon meridional circulation weakened obviously.