According to the internal structure of the nand flash memory and poor correct capability of traditional ECC of Hamming checking method, a kind of (4200,4096,8)BCH code for ECC verification is proposed. Parallel coding mode is chosen in this method. What’s more, parallel pipeline block decoding method is used for the decoder, which occupied most logical resource. With the method above, decoding efficiency is greatly increased. FPGA is selected as the verification platform, verification on this platform shows that the storage reliability is most significantly improved using BCH code for ECC verification. The proposed method has high practical value and reference for current large capacity storage is provided.