Using observations of sea surface temperature (SST) from HadISST and ERSST and the Coupled Model Intercomparison Project (CMIP) database in the 20th century, we analyzed the spatial variations in the long-term variation of SST over the tropical oceans in the twentieth century. The results displayed that the El Nino-Southern Oscillation (ENSO) and long term linear trend were the most significant signals, and this signal also displayed a long term linear trend. Observed Equatorial Indo-Pacific Sector SST exhibited a zonally asymmetric evolution: while the eastern part of the Equatorial Pacific showed only a weak warming, or even cooling in one SST dataset, the western part and the Equatorial Indian Ocean exhibited a rather strong warming. The zonally asymmetric correlated the eastern part of the Equatorial Pacific significantly. These results may be important in the context of global warming, as regional climate changes in the Equatorial Sector may critically depend on inter-basin interactions.