The terminal in Jieyang city will be able to receive 2.0 million tonnes of LNG per year when the first phase construction finishes, it said.
It didn't specify when the terminal will come onstream.
The capacity is far bigger than the expected first phase of 0.3 million tonne per year reported by media earlier.
Investment in the LNG project, including a terminal, pipeline and a wharf, totalled 10.3 billion yuan ($1.55 billion), it said.
The Jieyang terminal was the second LNG project CNOOC has begun building in Guangdong in the past two months.
In October, CNOOC started construction a LNG terminal in Zhuhai, also in Guangdong, which will have a capacity of 3.5 million tonnes per year when it is put into operation in 2013.