* SSEC +0.3 pct, CSI300 +0.5 pct, HSI 0.0 pct
* China to continue to open its economy, deepen reforms - Xi
* Leader pledges more efforts to reduce industry overcapacity
SHANGHAI, Oct 18 (Reuters) - China stocks rose on Wednesday morning, when a key party congress that investors hope will promote policies and reforms boosting the world's second largest economy opened in Beijing.
The twice-a-decade Communist Party congress is expected to cement the power of President Xi Jinping, who kicked off the week-long event with a speech saying the market would be allowed to play a decisive role in allocating resources.
Xi also said China will continue to open its economy and deepen financial reforms.
The CSI300 index rose 0.5 percent, to 3,931.78 points at the end of the morning session, and the Shanghai Composite Index gained 0.3 percent, to 3,381.27 points.
Investors are keen for direction on economic and financial market reform over the next five years, though history suggests these events can be light on detail.
"Market participants are paying much more attention to the party congress this time, as they are watching if any surprise reforms will emerge amid concerns over economic growth," said Yan Kaiwen, an analyst in Shanghai with China Fortune Securities.
Investors should have confidence that China's reforms will succeed, Yan said, asserting that ongoing supply-side ones have boosted economic growth.
Also lifting sentiment, China's central bank injected 300 billion yuan ($45.39 billion) into money markets on Wednesday, as Beijing moved to maintain balanced cash conditions.
Financial and utilities held steady, while the defensive consumer and healthcare firms led the gains.
But property developers lost 0.5 percent, after Xi said China will maintain the principle that houses are for people to live in, not for speculation.
In Hong Kong, the Hang Seng index was unchanged at 28,696.29 points.
The Hong Kong China Enterprises Index gained 0.4 percent, to 11,619.65 points.
(Reporting by Luoyan Liu and John Ruwitch; Editing by Richard Borsuk)