"China is a permanent member of the United Nations Security Council, so we are paying close attention to the evolving situation in South Sudan," he told reporters.
"We have been making mediation efforts, and the Chinese government special representative for African affairs is visiting the region and has had meetings with both sides," he added.
China is a key stakeholder in South Sudan, with heavy investment in the country's oil sector and as a buyer of most of its crude output.
"While I'm in Addis Ababa... I'm ready to directly engage the two parties and that I believe is also my responsibility," Wang told a news conference.
Wang is currently on the first leg of a four-nation African tour, and his Ethiopian visit coincides with peace talks between South Sudan's government and rebels being held in Addis Ababa.