A method for decoding a picket code data cluster is disclosed, wherein said picket code data cluster comprising synchronization codes and low protective code words. The method comprises steps (a) to (d). In step (a), any error of the synchronization codes is detected so as to generate sync erasure indicators. In step (b), the sync erasure indicators are stored into a memory. In step (c), erasure bits are generated, wherein each erasure bit corresponds to respective ones of the low protective code words if the sync erasure indicators which are close to said one of the low protective code words shows an error. In step (d), the low protective code words are decoded by using the erasure bits.