The present invention provides an apparatus and method for processing a packet. An interface processing module selects one from all service processing modules as a service processing module for processing a packet; if the service processing module needs to perform tunnel processing for the packet, the service processing module transmits the packet after performing the tunnel processing; if another service processing module needs to perform tunnel processing for the packet, the service processing module transmits the packet to a service processing module needing to perform tunnel processing for the packet. According to the present invention, the packet can be processed uniformly by the service processing module, so it is not unnecessary to store session states in the service processing modules, and also not unnecessary to perform synchronization between the service processing modules, which greatly decreases complexity of processing the packet and saves system bandwidth.