Crossover has been a most typical feature of the age of"Internet Plus". Crossover cooperation with other institutions could help libraries to introduce,integrate and utilize more social resources. Adopting both methods ofliterature review and fieldwork, this paper makes a survey of current libraries’ crossover cooperation, andsummarizes four main models. First,libraries could cooperate with the information industry,acting as a medium ofsocial information communication. Second,libraries could cooperate with other education agencies,acting as asocial education platform. Third,libraries could cooperate with other social institutions,acting as a main body ofreading promotion. Fourth,libraries could cooperate with cafes,teahouses,flower shops,etc.,acting as a partof the Third Space in cities.