Xi asked both sides in the Syrian conflict to find a political solution.
He said China is ready to enhance communication and coordination through the UN Security Council, and will continue its unremitting efforts to bring about a political settlement.
Leaders at the SCO summit endorsed the idea of placing Syria's chemical weapons under international control and gradually destroying them.
They also called for an immediate end to the violence, the start of inclusive political dialogue as soon as possible and for an international conference to be convened.
Chen Yurong, a senior researcher at the China Institute of International Studies, said: "China and Russia have long held consistent stances on the Syria issue. They object to the use of armed force and outside intervention, and insist on respect of a country's sovereignty and the UN's leading role.
"We can see that Russia and China's stance has won widespread support."
At the SCO summit, the leaders also vowed to jointly fight terrorism, extremism and separatism, as well as drug smuggling and transnational organized crime.
Li Wei, director of the Institute of Security and Arms Control Studies at the China Institutes of Contemporary International relations, said the SCO is crucial for China's national security, because the most direct terrorist threat to China, "East Turkistan" forces, is spreading in the region.
Chen said security cooperation has always been the highest priority at SCO summits.
"The organization was originally established to protect stability in Central Asia. Now, the region is facing complex security challenges, including the impact from continuing turmoil in the Middle East and North Africa and the aftermath of US troops withdrawing from Afghanistan, which will be completed in 2014."
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