The Afro-Asian summer monsoon system includes the African summer monsoon,the South Asian summer monsoon and the East Asian summer monsoon.It is considered to be a subsystem of the global monsoon system,characterized with a highly consistent variability,which is mainly due to the same main driving forces.For example,there are oceanic multi-decadal variability modes in the North Atlantic and northern Pacific oceans,which are referred to as the AMO(Atlantic Multi-decadal Oscillation) and PDO(Pacific Decadal Oscillation) oceanic modes,respectively.Therefore,starting from this point,this paper has first analyzed the forcing and teleconnection effects of the AMO mode on the Afro-Asian summer monsoon,with a special emphasis placed upon the role of the AMO in the interdecadal transitions of the Afro-Asian summer monsoon and the occurring rainfall rate.Second,this paper has discussed the coordinated effects of the PDO and the preceding winter and spring snow coverage over the Tibetan Plateau on East Asia summer monsoon rain belts.Then,on the above-mentioned basis,the coordinated effects of the AMO,PDO and IOBM(Indian Ocean Basin Mode) are clearly identified.It should be pointed out that the IOMB oceanic mode is considered to be independent from the combined effects of the AMO and PDO oceanic modes in regard to the interdecadal scale effects,and has mainly played an enhancement role in the activities of the East Asian summer monsoon.