Shen Danyang, the spokesman of China's Ministry of Commerce, made the revelation Tuesday in Beijing.
Shen says the two sides agreed on the exchange of negative list offers in early September.
Chinese President Xi Jinping is also scheduled to pay a state visit to the US in that month.
The investment treaty talks began in 2008 as China and the U.S. sought to increase mutual investment.
The negative lists exchange is a key step in the negotiations.