Based on the reconstructed SST (sea surface temperature) data from NOAA and atmospheric reanalysis data from NCEP, the interdecadal variability of the relationship between ENSO (El Niño-Southern Oscillation) and SCS (the South China Sea) SST is studied. It is found that the anomalous SCS SST double peak structure affected by ENSO in winter and summer has undergone significant interdecadal variability, that is, the winter peak has weakened significantly since the 1980s, while the summer peak remains stable and has been enhanced since the 1970s. The weakening of the winter peak may be related to the interdecadal variability of the western North Pacific anticyclones in winter, and the maintenance and enhancement of the summer peak may be associated with the enhancement of the capacitor effect of SST over the Indian Ocean after the 1970s.