A network interface card with a packet filtering function and a filtering method thereof are applicable to realize packet filtering through both software and hardware manners. The network interface card includes a connection port, a first filtering module, a second filtering module, and a storage unit. The connection port is used to receive a packet data from Internet. The first filtering module is connected to the connection port, and is used to detect the packet data according to a content address memory (CAM) table. The detecting process is executed by a firmware of the network interface card. The second filtering module is connected to the first filtering module, and executes a packet content detecting procedure for detecting a content of the packet data, thereby detecting the packet data by using software/firmware respectively, and thus a working efficiency of the network interface card is enhanced.