A method, an apparatus, and a system for accessing service by a Mobile Station (MS) are provided by the present disclosure. The method comprises the following steps: Gateway General Packet Radio Service (GPRS) Support Node (GGSN) or a next level gateway of the GGSN receives a service request carrying Virtual Access Point Name (VAPN) or a service request not including APN transmitted from a MS, performs a Deep Packet Inspection (DPI) processing to the service request, and identifies the type of the service; GGSN or the gateway sends the service request to the external data network corresponding to the service type. Therefore, accessing various types of mobile data services can be achieved through the service identification function of GGSN or GGSN gateway without modifying MS APN configuration by the mobile MS, therefore the service experiences for a MS user is enhanced effectively.