I'm doing a presentation on the influence of countries outside Europe in the foundation of the United Nations, I think China had some influence but I'm not sure!
There were 26 signatories to the Declaration of the United Nations on January 1, 1942. They included the following:
1) The Big Four, United States, United Kingdom, Soviet Union, and the (Nationalist) Republic of China.
2) Five British Commonwealth countries outside of Europe: Australia, New Zealand, Canada, India, South Africa.
3) Nine small countries in the western hemisphere: Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama in Central America, and Cuba, the Dominican Republic, and Haiti in the Caribbean.
4) Eight governments in exile in Europe: the Czech Republic, Greece, Norway, Poland, Yugoslavia, and the three "Benelux" countries.
So the non-European countries you'd be interested in are Australia, China, India, New Zealand, South Africa, and the non-U.S. western hemisphere countries.The whole point was to make this a global, and not "European" alliance.
Wikipedia has a good synopsis of the founding https://en.wikipedia.org/wiki/United_Nations#Founding
But you are right, that China was involved in the founding. China was one of the big guys on the "Good" or winning side of WW2. As such they had a degree of weight in diplomatic talks as well as an interest in the development of the new order. However, it should be noted that the "China" involved was not the "China" of today. China was not in the control of the Communists at that time.
EDIT: Map of the member states and their join dates https://en.wikipedia.org/wiki/History_of_the_United_Nations#/media/File:United_Nations_member_countries_world_map.PNG