A network apparatus and a method of switching a data network for a network apparatus are provided. The network apparatus includes a plurality of User Identity Modules (UIMs), a transceiver module, and a switching unit. The UIMs are used to provide a plurality of network service plans, wherein the network apparatus operates in a first network service plan corresponding to a first UIM of the UIMs. The transceiver module is arranged to receive a plurality of network packets corresponding to the network service plans. The switching unit is arranged to obtain a plurality of corresponding network connection information from the network packets, performing an information-matching operation upon the plurality of corresponding network connection information to generate a matching result by referring to a profile database, and determining if the network apparatus is required to be switched to operate in a second network service plan according to the matching result.