The spatial and temporal variation characteristics of the waves in the South China Sea(SCS) in the boreal winter during the period of 1979/1980–2011/2012 have been investigated based on the European Centre for Medium-range Weather Forecasts interim(ERA-Interim) reanalysis dataset. The results show that the leading mode of significant wave height anomalies(SWHA) in the SCS exhibits significant interannual variation and a decadal shift around the mid-1990 s, and features a basin-wide pattern in the entire SCS with a center located in the west of the Luzon Strait. The decadal change from a weak regime to a strong regime is mainly associated with the enhancement of winter monsoon modulated by the Pacific decadal oscillation(PDO). The interannual variation of the SWHA has a significant negative correlation with the El Ni?o Southern Oscillation(ENSO) in the same season and the preceding autumn. For a better understanding of the physical mechanism between the SCS ocean waves and ENSO, further investigation is made by analyzing atmospheric circulation. The impact of the ENSO on the SWHA over the SCS is bridged by the East Asian winter monsoon and Pacific-East Asian teleconnection in the lower troposphere. During the El Ni?o(La Ni?a), the anomalous Philippine Sea anticyclone(cyclone) dominates over the Western North Pacific, helps to weaken(enhance) East Asian winter monsoon and then emerges the negative(positive) SWHA in the SCS. The spatial and temporal variation characteristics of the waves in the South China Sea (SCS) in the boreal winter during the period of 1979 / 1980-2011 / 2012 have been investigated based on the European Center for Medium-range Weather Forecasts interim (ERA- The results show that the leading mode of significant wave height anomalies (SWHA) in the SCS exhibits significant interannual variation and a decadal shift around the mid-1990 s, and features a basin-wide pattern in the entire SCS with a center located in the west of the Luzon Strait. The decadal change from a weak regime to a strong regime is primarily associated with the enhancement of winter monsoon modulated by the Pacific decadal oscillation (PDO). The interannual variation of the SWHA has a significant negative correlation with the El Niño Southern Oscillation (ENSO) in the same season and the preceding autumn. For a better understanding of the physical mechanism between the SCS ocean waves and ENSO, furth The impact of the ENSO on the SWHA over the SCS is bridged by the East Asian winter monsoon and Pacific-East Asian teleconnection in the lower troposphere. During the El Niño (La Niña ), the anomalous Philippine Sea anticyclone (cyclone) dominates over the Western North Pacific, helps to weaken (enhance) East Asian winter monsoon and then emerges the negative (positive) SWHA in the SCS.