This paper presents a majority-logic based message-passing algorithm for decoding non-binary LDPC codes. Recently, many majority-logic decoding (MLGD) algorithms make huge efforts on reducing the computational complexity for decoding non-binary LDPC codes. Inspired by one step majority-logic decoding and q-ary sum-product algorithm, we devise a novel iterative double-reliability-based (IDRB) MLGD algorithm which carries out an efficient trade-off between decoding computational complexity and error performance. The proposed algorithm achieves a remarkable enhancement on error correct ability and yet requires only integer operations and finite field operations. Simulation results on two NB-LDPC codes show that we succeed in achieving significant coding gain compared with IHRB- and ISRB-MLGD with limited complexity increase.