The blue-chip CSI300 index was unchanged at 4,883.32, while the Shanghai Composite Index lost 0.3% to 3,521.79 points.
U.S. President Joe Biden and Chinese leader Xi Jinping stressed their responsibility to the world to avoid conflict as the heads of the two top global economies gathered for hours of talks on Monday.
Investors had expected the summit to help stabilize China-U.S. ties by opening negotiations over the conflicting areas.
The defence sub-index dropped 3.9% amid easing tensions between U.S. and China in the meeting.
Consumer staples gained 1.6%, with liquor makers surging nearly 4%. Healthcare shares went up 2.7%.
Several Chinese food companies have increased the prices of their products since last month due to rising raw material and transportation costs.
Haitong Securities said PPI may have already peaked and could fall in the fourth quarter, which would reduce the cost pressure for companies and bring more opportunities in the consumer sector.
On the second trading day of the new Beijing Stock Exchange, only 7 shares of the first batch of 81 companies went up.
