Abstract: With the emergence of the mass collaboration paradigm along with the rapid development of Internet Communication Technologies (ICTs), the wide acceptance of mass collaboration is inevitable with its irresistible advantages in transmitting, sharing and integrating knowledge among participants. In this context, initiatives in creating practical and sustainable knowledge networks are highly desired. As an explorative initiative supported by the International Geographical Union (IGU), www.oursus.org with its Chinese and English-version websites, a Global Sustainable Development Cities Information Network (IGU-GSCIN), was put forward in 2010 adopting a so-called rainbow knowledge category approach, task modules for different role participants and the most popular ICTs, such as social networks and location-based systems. Taking an action research approach, we believe that it is quite possible for this kind of website to develop as a multi-dimensional knowledge network for global sustainable cities which includes products with sustainable features provided by enterprises, cases and problem observation by NGOs and experts, experience exchange by individuals, campaigns by volunteers, etc.