Leaders from almost 30 nations have met in Beijing to discuss what is being termed the One Belt One Road initiative.
Chinese president Xi Jinping's plan is to expand links between Asia, Africa and Europe and build a vast network of trade routes spanning 65 countries.
China has touted it as a new way to boost development ever since Mr Xi unveiled the plan in 2013.
His vision is to develop economic links, establish a series of free-trade zones and build high-speed rail networks, ports and other facilities.
He has pledged US$124 billion for his ambitious new plan.
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"Now, today, we carry forward the spirit of the ancient Silk Road and gather to discuss the Belt and Road construction, which follows the historical trend and forges the right path for continuing forward into the future. It condenses all desires of all human beings into one common dream, that is, a dream that comes true in truthful reality in which each and every of us live happily thereafter."
A number of countries have welcomed the investment, saying it is broad on ambition.
Germany's economic minister, Brigitte Zypries, says Germany welcomes China's initiative, too.
But she said Germany wanted certain keywords included in a communiqué being published at the end of the forum.
She said, without them, European Union representatives attending the forum could not sign it.
"We'll see what happens with the joint communique. For the moment at least, the demands of the countries in the EU is that certain keywords like free trade, level playing field and equal treatment are included. These demands haven't been met, and, for this reason, at the moment, we are saying, if this doesn't happen, then we can't sign."
Some other governments have expressed their own concerns.
India's main objection is that a key part of the plan will run through the disputed Kashmir.
Japan has expressed unease over China's development agenda, worried it is about increasing the country's political stature.
Speaking before an audience that included Russian president Vladimir Putin, Mr Xi said his government has no desire to impose its will on others.
He urged countries to support the plan, saying it is aimed only at promoting prosperity.
"The Chinese are willing to develop friendly cooperation with all participating countries for the Belt and Road plan under the Five Principles of Peaceful Coexistence. China is willing to share our development experience but will not interfere in internal issues of other countries. China will not export, or force to promote, social systems or development formats to others."
The Asian Infrastructure Investment Bank is an active partner in the Belt and Road initiative.
The bank's president, Jin Liqun, has told China Central Television the AIIB is open to the world and is not restricted to only Asian-based programs.
"The AIIB proposed by President Xi mainly focuses on Asia, but aims to have cooperative programs in other areas. After the rise of China, we care about people around the world. So our bank's charter is open and inclusive. Our focus is on Asia, but not restricted to Asia, which has been clearly defined in our charters. Why is this so? Asia cannot stand alone and remain intact. Asia must work with Europe, Africa and America. Today, we talk about building Belt and Road together, which means wide consultation, joint construction and shared benefits. This principle coincides with our bank's principles."
Delegates at the forum have attended sessions focusing on such areas as policy coordination, financial integration and research-centre exchanges.
Participants have shared ideas, research, reports and concerns, as well as signing various bilateral and multilateral cooperation documents.
