Ban's trip comes ahead of a U.N. Security Council vote this week on whether to allow sanctions and military intervention in Syria if Assad's regime or insurgent forces fail to comply with a U.N. peace plan. Russia and China have blocked previous efforts to sanction Syria.
Ban was to hold talks with Chinese President Hu Jintao on Wednesday, with Syria expected to top the agenda.
There has been heightened urgency to global diplomatic efforts on Syria since it was reported last week that dozens were killed in a regime assault on the Syrian village of Tremseh. U.N. observers said the attack appeared to target army defectors and activists.
Syria has denied U.N. claims that government forces used heavy weapons such as tanks, artillery and helicopters during the attack.
In response to the Tremseh attacks, Ban on Friday urged U.N. members to "take collective and decisive action" on Syria immediately and warned that inaction would be "license for further massacres."
China has maintained that a diplomatic solution is the only way to end the crisis and resisted calls to pressure Assad to step down. The official People's Daily newspaper ran a commentary Tuesday strongly opposing force against Syria and calling for a political solution, a sign that China may again block the Western-backed resolution when it goes to a vote Wednesday.
"Sovereign equality and noninterference in internal affairs (of other countries) is a red line that must not be crossed," said the commentary. "A political solution is the only way out of the Syrian problem."
Syria's violence has grown increasingly bloody and chaotic in recent months as the uprising has morphed from a peaceful protest movement seeking political change into an armed insurgency seeking to topple the regime by force.
Anti-regime activists say more than 17,000 people have been killed, and the government says it has lost more than 4,000 security officers. It does not provide numbers of civilian dead.
International diplomacy has failed to stop the violence, and world powers remain deeply divided over who is responsible and how to stop it. The U.S. and many Western nations have called on Assad to leave power, while Russia, China and Iran have stood by the regime.
"I think Ban's message on the Syria problem will be very clear and quite urgent," said Shi Yinhong, an international relations professor at People's University in Beijing. "He hopes this time that China will give support to calls for Assad to step down. Or at least not to oppose them."
Shi said the violence in Tremseh has made it more difficult for China to oppose action against Assad's government but Beijing will also want to continue to align its position with Russia's.
"It would be hard for China to speak out if Russia sticks to its previous stance," Shi said. "China is in a very difficult situation now."
International envoy Kofi Annan, who has made little progress in brokering a political solution in Syria, met Russian leaders in Moscow on Monday. The meeting - the latest in Annan's efforts to save his faltering peace plan - comes a day after the conflict crossed an important symbolic threshold, with the international Red Cross formally declaring it a civil war, a status with implications for potential war crimes prosecutions.