The invention provides a system and a method for identifying public traffic information service demands based on XML (Extensive Makeup Language) for realizing a plurality of traffic information Web services executed by an original transportation mapping. The system comprises a storage device for storing an XML demand identification template and XML traffic service description documents, a traffic information service demand acquisition device, a traffic information service demand decomposition device, a traffic information service demand mapping device and an XML document generation device. The invention adopts an XML language which is a pure data descriptive language with good openness as an information description method, provides a friendly interaction interface for travelers, provides a clear Web service demand list for the matching and synthesis of Web services and further improves the efficiency of a public traffic information service system.