1. An efficient Chien search method in Reed-Solomon decoding, which is adapted to be implemented in a processor having a parallel processing instruction set, the efficient Chien search method comprising the following steps: (a) calculating an error evaluation value; (b) subjecting the error evaluation value to mapping processing so as to find an index adjusting value; (c) storing a symbol index into an error location memory corresponding to a location index; (d) updating the location index according to the index adjusting value; (e) updating the symbol index; and (f) repeating steps (a) to (e) a particular number of times.