By Summer Zhen

HONG KONG, May 15 (Reuters) - China stocks opened largely flat on Friday as investors remained cautious into day two of a high-stakes summit between U.S. President Donald Trump and China's Xi Jinping that has so far delivered few surprises.

China’s blue-chip CSI300 Index .CSI300 and the Shanghai Composite Index .SSEC were little changed, while Hong Kong’s benchmark Hang Seng .HSI also opened flat.

The two leaders are scheduled to have tea and lunch before Trump flies back to the United States.

Xi told ​Trump on Thursday that negotiations on trade issues had reached "balanced and positive outcomes", without elaborating.

Gary Tan, portfolio manager at Allspring Global Investments, said the summit could act as a strategic springboard for further engagement.

"As market expectations for any immediate breakthrough entering the summit are already low, any signs of incremental progress should be taken positively by the market," Singapore-based Tan said.

Trump told Fox News Channel that China has agreed to buy 200 Boeing BA.N jets, a number that was far fewer than analysts had expected.

It was undecided whether the trade truce will be extended after it expires later this year, U.S. Trade Representative Jamieson Greer told Bloomberg TV on Friday, but added deals had been firmed up on Chinese purchases of farm goods, beef and Boeing aircraft.

China's yuan CNY=CFXS maintained its strength as the Trump-Xi meeting was underway. The currency hit a three-year high against the dollar in the previous session.

The yuan eased slightly after the People's Bank of China set the midpoint rate CNY=PBOC at 6.8415 per dollar, 439 pips weaker than a Reuters' estimate.

The yuan is up 0.7% against the dollar this month, and 3.1% firmer this year.