Abstract: Using monthly reanalysis datasets of NCEP/NCAR for 1979-2015, the impact of anomalous water vapor transport from the tropical Indian Ocean-western Pacific on summer precipitation in eastern China was analyzed in this paper. The results show that the summertime anomalous water vapor transport from the tropical India Ocean-western Pacific (10°S-30°N, 60°-140°E) to eastern China mainly includes two modes, which can explain 34% of the total water vapor transport variance. The first mode (EOF1) shows anomalous water vapor transport from the tropical western Pacific across the South China Sea and the Bay of Bengal to eastern China along the western flank of the anticyclone. The water vapor transport from the South China Sea and the Bay of Bengal both are abnormally high. Meanwhile, the WPSH (western Pacific subtropical high) is significantly stronger than normal, and anomalous water vapor convergence occurs over the middle and lower reaches of the Yangtze River valley accompanied with significant upward movements, which are favorable for precipitation over this region. The second mode (EOF2) shows anomalies of anticyclonic water vapor transport from the tropical India Ocean across the Arabia sea, India Peninsula, and Indo-China Peninsula and anomalies of cyclonic water vapor transport over southern China, which lead to anomalous water vapor convergence and ascending motions over southern China. As a result, more precipitation occurs in southern China. Furthermore, possible external causes for the above two modes were analyzed. Results indicate that the EOF1 is closely related to ENSO. SST (sea surface temperature) over the tropical eastern Pacific in the preceding winter was significantly warmer than normal, while SSTs over the tropical North India Ocean and the South China Sea in the subsequent summer were significantly warmer than normal. These SST anomalies resulted in a significantly strong WPSH and anomalously high water vapor mainly originated from the tropical western Pacific and the South China Sea. The EOF2 is related to the simultaneous positive phase of the tropical Indian Ocean Dipole (IOD). The anomalous easterly winds appeared over the tropical India Ocean when the IOD was positive phase, which was linked to anomalous cyclonic circulation and moisture convergence over South China. The anomalous water vapor mainly originated from the tropical southern India Ocean.