A method, performed by a mobile terminal, to select a network, comprising: acquiring shared network configuration information set in advance and determining, according to the shared network configuration information, whether a home network of a local SIM card is a shared network; when the home network of the local SIM card is a shared network, then selecting, from all shared networks, an optimal shared network and implementing a registration operation of the optimal shared network; wherein: the shared network configuration information comprises: an identity, ID of each shared network and network capability information of each shared network; wherein a network capability of each shared network is a maximum capability which the shared network supports, the network capability comprising High Speed Downlink Packet Access, HSDPA, High Speed Uplink Packet Access, HSUPA, High Speed Packet Access Plus, HSPA+, Dual Carrier High Speed Packet Access Plus, DC-HSPA+ and Long Term Evolution, LTE; the network capability of the shared network being indicated by an integer, wherein the greater the value of the integer is, the higher the theoretical download rate it supports and the stronger the network capability is; the step of selecting from all shared networks an optimal shared network comprises: determining whether a network capability of each shared network of all shared network is consistent with each other; when it is determined that the network capability of each shared network of all shared networks is not consistent with each other, then selecting from all shared networks a shared network having a strongest network capability as the optimal shared network. acquiring shared network configuration information set in advance and determining, according to the shared network configuration information, whether a home network of a local SIM card is a shared network; when the home network of the local SIM card is a shared network, then selecting, from all shared networks, an optimal shared network and implementing a registration operation of the optimal shared network; wherein: the shared network configuration information comprises: an identity, ID of each shared network and network capability information of each shared network; wherein a network capability of each shared network is a maximum capability which the shared network supports, the network capability comprising High Speed Downlink Packet Access, HSDPA, High Speed Uplink Packet Access, HSUPA, High Speed Packet Access Plus, HSPA+, Dual Carrier High Speed Packet Access Plus, DC-HSPA+ and Long Term Evolution, LTE; the network capability of the shared network being indicated by an integer, wherein the greater the value of the integer is, the higher the theoretical download rate it supports and the stronger the network capability is; the step of selecting from all shared networks an optimal shared network comprises: determining whether a network capability of each shared network of all shared network is consistent with each other; when it is determined that the network capability of each shared network of all shared networks is not consistent with each other, then selecting from all shared networks a shared network having a strongest network capability as the optimal shared network. the shared network configuration information comprises: an identity, ID of each shared network and network capability information of each shared network; wherein a network capability of each shared network is a maximum capability which the shared network supports, the network capability comprising High Speed Downlink Packet Access, HSDPA, High Speed Uplink Packet Access, HSUPA, High Speed Packet Access Plus, HSPA+, Dual Carrier High Speed Packet Access Plus, DC-HSPA+ and Long Term Evolution, LTE; the network capability of the shared network being indicated by an integer, wherein the greater the value of the integer is, the higher the theoretical download rate it supports and the stronger the network capability is; the step of selecting from all shared networks an optimal shared network comprises: determining whether a network capability of each shared network of all shared network is consistent with each other; when it is determined that the network capability of each shared network of all shared networks is not consistent with each other, then selecting from all shared networks a shared network having a strongest network capability as the optimal shared network. determining whether a network capability of each shared network of all shared network is consistent with each other; when it is determined that the network capability of each shared network of all shared networks is not consistent with each other, then selecting from all shared networks a shared network having a strongest network capability as the optimal shared network.