Low Density Parity Check (LDPC) codes have been extraordinarily important in the field of communications because its error-correction approximates to Shannon limit. Binary LDPC codes have been applied in many fields, and relatively Non-Binary (NB) LDPC codes have recently attracted considerable attention on account of their better error performance. Common NB-LDPC codes decoding algorithm involves Belief Propagation (BP) algorithm, Fast Hadamard Transform-BP (FHT-BP) algorithm, etc. The decoding performance of each algorithm has a certain upper limit. In this paper, the code word structure of NB-LDPC codes is considered, and the decoding of LDPC codes under Galois Field(4) (GF(4)) is mainly indicated. On the basis of the FHT-BP algorithm, Multi-Layer Perceptron (MLP) neural networks and bit flipping (BF) method are introduced for joint decoding. This method can improve the error performance of LDPC codes and achieve better decoding results.