The summit coincides with the 15th anniversary of the six-nation group that works together on anti-terrorism, security and other issues.
In a signed article published in a local newspaper, Xi said this year's summit is of great significance in summarizing experiences and charting future cooperation plans.
The major document to emerge from the summit is expected to be the Action Plan for 2016-20. This includes specific measures in areas such as politics, security, economic affairs and culture, according to Uzbekistan's Deputy Foreign Minister Anvar Nasirov.
Sun Zhuangzhi, an expert on Russian studies at the Chinese Academy of Social Sciences, said that although the SCO is 15 years old, internal economic cooperation remains inadequate.
The Silk Road Economic Belt — which links China with Europe through Central and Western Asia — will inject new momentum into members' economies, Sun said.
The accession of Pakistan and India to the organization will be another key issue at the summit, according to officials from member countries.
By An Baijie in Tashkent and Zhang Yunbi in Beijing (China Daily)