Cross-spectrum revealed the coupling relationships between the Nansha sea surface temperature (SST), the Central and Eastern Equatorial Pacific SST, Southern Oscillation (the difference between the standardized sea level pressure at Darwin and Tahiti)and the Western Pacific Subtropical High. The results showed that there are apparent coupling periods of 2,5 and 23.3-46.5 months among them, and the inphase low-frequency coupling oscillation of 2-3.8 years period is predominant and associated with the ENSO events. The physical processes affecting the Nansha SST are discussed. During the ENSO events, the Central and Eastern Equatorial Pacific SST increase, then the Western Subtropical High develops and extends westward. The cloudiness over the Nansha area decreases, the Nansha SST increases, and vice versa. The variations of cludiness over the Nanhai (weak ocean current area) play an important role in influencing the Nansha SST under the control of the Western Subtropcal High.