Method and terminal for realizing business in GSM and 3G network coexisted network

The terminal accomplishes following steps: when being started up, through guidance of message of GSM network system and message of 3G network system, the terminal resides GSM network first; after detected user initiated service type being as 3G feature service, and 3G signal, the terminal starts up cell reselection between systems first; after reselecting 3G network, the terminal initiates request of 3G feature service to 3G network. The invention also discloses terminal implements services in coexistent network between GSM and 3G network. Under condition of incomplete coverage of 3G network, the invention implements voice service and 3G feature services preferably.