The 500,000-barrel cargo of Access Western Blend (AWB) crude will be delivered to Rongsheng's refinery in Zhoushan in August, they added.
The price was not immediately available.
Separately, Rongsheng also bought 2 million barrels of Abu Dhabi Upper Zakum crude from Aramco Trading at 60 cents a barrel above July Dubai quotes before freight charges in the tender, the sources said.
The Chinese refiner also purchased 2 million barrels of West African crude consisting of Djeno and Mostarda at $2.50-$3 a barrel above July dated Brent from Unipec, they added.
The companies do not comment on commercial deals.