Embodiments of the present invention provide a decoding apparatus and method. The method includes: obtaining a to-be-decoded group; detecting whether all code words in the to-be-decoded group meet that a checksum is 0; performing a sign bit decision on the to-be-decoded group when all the code words in the to-be-decoded group meet that a checksum is 0; detecting, when all the code words in the to-be-decoded group do not meet that a checksum is 0, whether the sign bit decision has been performed on each code word in the to-be-decoded group; performing, when there is at least one code word on which the sign bit decision has been performed in the to-be-decoded group, data restoration on each code word on which the sign bit decision has been performed; and constructing a new to-be-decoded group by using each code word obtained after the data restoration and each code word on which the sign bit decision has not been performed, to perform FEC decoding. When all the code words in the to-be-decoded group meet that a checksum is 0, FEC decoding is not performed, and only the sign bit decision is performed. That is, in a process of performing multiple times of decoding on each code word, FEC decoding is not always performed every time. This reduces power consumption required by FEC decoding.