Sun, who is headed to New Delhi on Saturday to take charge of his office, spoke to the Indian media in Beijing on a range of issues ranging from border dispute to trade deficit and US' trade war to the forthcoming informal summit between President Xi Jinping and Indian Prime Minister Narendra Modi.
Sun, who is China's one of the finest diplomats and an expert on South Asia, said this second informal summit between Xi and Modi later this year will take the Sino-Indian relations to a new height.
The envoy suggested India and China make a joint front against the US that has taken on both the countries on the trade front.
"There has been a change that is unseen in this century. Like I just mentioned the ugly path of unilateralism and protectionism has now affected the growth and stability of the world economy," Sun said.
"This will surely have an impact on the emerging markets and the developing countries because it also based on the international order that relies on that," Sun added.
"In this changing world, China and India have all the reasons to work together to safeguard our common interests and promote a more fair and open international economic order. Also to realise our mutual and common interests, it is very important."
China and the US have been engaged in the world's biggest trade war, slapping tariffs worth billions of dollars on each other's products. Washington triggered it last year, claiming Beijing's business practices are unfair, a charge denied by the Chinese government.
Experts say India could be Washington's next target after the US ended preferential trade status that had allowed Indian goods to enter America without duties. India retaliated by slapping additional duties on US products which American President Donald Trump described as "unacceptable."
Some experts say US' trade offensive could bring regional rivals India and China together take on Washington temporarily.
In his interaction at Chinese foreign ministry, Sun' tone suggested that.
"China and India are the only two emerging markets and developing countries in the world that have a population of over one billion.
"So while upholding our legitimate rights and interests, we have to shoulder our historical responsibility in terms of safeguarding peace, stability, and prosperity for the world as well as injecting positive energy and stabilizing that.
"So specifically speaking we should stick to multilateralism and defend the international system with the UN at the core and try to promote multilateralism in the world order and try to make it more democratic."
"We also have to try to resolve dispute and issues through political dialogue. We also need to advance the WTO reforms and through promoting trade and investment liberalization, we also need to build an open world economy that is beneficial to the developing countries."
( With inputs from IANS )