Quan sealed a China one-two in the women's 10m platform, her winning total of 425.60 points keeping team-mate Chen Yuxi at bay for silver with 420.70.
North Korea's Kim Mi Rae took bronze on 372.10, and promptly burst into tears.
Quan also won the 10m platform at the Tokyo Olympics, when she was just 14, and then took gold in the women's synchronised 10m platform in Paris with Chen.
China are the unrivalled superpower in diving and have won all five golds in the sport so far in the French capital.
Three more golds are up for grabs.
China's divers won all but one of the eight titles in Tokyo, Britain took the other.
