1. A method for detecting an abnormality of a network processor, comprising: adding an abnormality detection operation code into an execution flow of each thread in a network processor, and setting a flag bit corresponding to a current thread in an abnormality protection flag data area in a shared memory to a first flag by the network processor when executing the abnormality detection operation code in the current thread; and when a period of a timer is expired, detecting, by a coprocessor, all the flag bits in the abnormality protection flag data area in the shared memory, determining that a thread corresponding to a flag bit which is not the first flag is abnormal when detecting that not all the flag bits are the first flag, and setting all the flag bits to a second flag when detecting that all the flag bits are the first flag.