The present invention is applicable to the field of error correction coding, and provides a circuit, an encoder and a method for parallel BCH coding. The method comprises: performing an XOR operation on input sequences {m(p−1), m(p−2), . . . , m(0)} in a current period in sequence corresponding to output upper bits of the previous period of a register separately, outputting operation results as selection signals to a selector, selecting P constant-multinomials {xr