Abstract: With a changeable geological environment, there exist several viewpoints on the chronology of Quaternary sediments in the modern Pearl River Delta region. Based on AMS 14C and optically stimulated luminescence (OSL) dating in conjunction with sea level records from the South China Sea, the authors have found that the age of the oldest Quaternary sediments at the bottom of drill hole QZK4 is about 43.71ka BP, which is located at the center of the Pearl River Delta region. The Quaternary environment recorded is responding well to the sea level changes reconstructed from the South China Sea in the drill core: the fluvial deposits and the weathered layers were formed during a low stand of the sea level from the last glacial period to the early Holocene, and the estuarine-coastal sediments were deposited following the high stand of sea level since the early to middle Holocene. It is inferred that the bottom of Quaternary sediments in the modern Pearl River Delta region is probably older than the record from this drill hole according to the environmental analysis.