A method for data service transmission, wherein the method comprises: when arriving in a roaming region, receiving, by a terminal, a first message sent by a network operator in the roaming region, wherein the first message carries identification information of a virtual subscriber identity module, SIM, card of the network operator in the roaming region; after succeeding in network authentication of the network operator in the roaming region, downloading, by the terminal, virtual SIM card information according to the identification information of the virtual SIM card in the first message; storing, by the terminal, the virtual SIM card information separately according to a security level of the virtual SIM information: storing an authentication key and an authentication algorithm in the virtual SIM information in a secure operating system, and storing the remaining of the virtual SIM information in an encrypting file system EFS; after the storing, by the terminal, the virtual SIM card information separately according to a security level of the virtual SIM information, further comprising: if the terminal is in a manual selection mode, receiving, by the terminal, the virtual SIM card information, selected by a user, and performing configuration according to the virtual SIM card information selected by the user; and using, by the terminal by utilizing the virtual SIM card, a service provided by the network operator in the roaming region to perform service transmission. when arriving in a roaming region, receiving, by a terminal, a first message sent by a network operator in the roaming region, wherein the first message carries identification information of a virtual subscriber identity module, SIM, card of the network operator in the roaming region; after succeeding in network authentication of the network operator in the roaming region, downloading, by the terminal, virtual SIM card information according to the identification information of the virtual SIM card in the first message; storing, by the terminal, the virtual SIM card information separately according to a security level of the virtual SIM information: storing an authentication key and an authentication algorithm in the virtual SIM information in a secure operating system, and storing the remaining of the virtual SIM information in an encrypting file system EFS; after the storing, by the terminal, the virtual SIM card information separately according to a security level of the virtual SIM information, further comprising: if the terminal is in a manual selection mode, receiving, by the terminal, the virtual SIM card information, selected by a user, and performing configuration according to the virtual SIM card information selected by the user; and using, by the terminal by utilizing the virtual SIM card, a service provided by the network operator in the roaming region to perform service transmission. if the terminal is in a manual selection mode, receiving, by the terminal, the virtual SIM card information, selected by a user, and performing configuration according to the virtual SIM card information selected by the user; and using, by the terminal by utilizing the virtual SIM card, a service provided by the network operator in the roaming region to perform service transmission.