Biodiversity loss is on the list of the most challenging issues the world sustainability faces. This study aims to examine the global illegal ivory trades, identify key hub countries and map the key smuggling routes in the worldwide illegal ivory trading network. A social network analysis (SNA) and a set of network indicators are used to investigate CITES’s (Convention on International Trade in Endangered Species of Wild Fauna and Flora) ivory trading data from 1975 to 2017. Several important conclusions are derived: (1) The social network of global ivory trading is closely connected, with an average path length of 2.643 and an average clustering coefficient of 0.463. An average of 45,410.384 kg of ivory products was trafficked from each of the 182 countries to an average of another 8.17 countries. The dynamic networks of global ivory trading show the pattern of high connectivity and high aggregation. (2) The USA, the UK, Zimbabwe, South Africa, China, Japan, Sudan, Belgium and Hong Kong are the most important hubs in the worldwide ivory trade according to degrees and centralities in the SNA. (3) According to trading weight density, three significant ivory trafficking routes are illustrated: 1. African countries (Sudan, Zimbabwe, South Africa, Central African Republic, the Republic of Congo, Somalia and Uganda) to Hong Kong; 2. Belgium to Hong Kong and Japan; 3. Mutual transactions between Japan and Hong Kong. The analytical framework in this study can also be useful for studying other illegal trading activities, like other animal trades, with respect to biodiversity conversation, and could serve as a reference for other network-based sustainability challenges, such as human migration, biological invasion, and waste smuggling and dumping.