An apparatus and method for blocking abnormal communication are disclosed herein. The apparatus for blocking abnormal communication includes a packet collection unit, a packet analysis unit, and an access control unit. The packet collection unit collects a packet via a network device. The packet analysis unit generates a system rule, a communication flow rule, and a packet characteristic rule based on the packet from the packet collection unit. The access control unit determines whether to block the packet by determining whether the packet from the packet collection unit satisfies the system rule, the communication flow rule and the packet characteristic rule.