Abstract: Compared with Turbo codes, nonbinary low-density parity-check (LDPC) codes have the better waterfall and error floor performance. The nonbinary LDPC codes are applied to decode-and-forward (DF) cooperative communications in this paper, and a multiuser cooperative scheme based on outage probability is proposed. Each user decides its relay by judging whether its channel to the source node is in outage or not. In case the channel is not in outage, the user decodes the received signal from the source node, and encodes it using nonbinary LDPC codes before forwarding to the destination. The parity-check matrix of nonbinary LDPC codes consists of information part and parity-check part. The information part is quasi-cyclic, and the parity-check part is the dual-diagonal structure. Simulation results show that, compared with the random cooperative scheme, the proposed scheme can achieve about 0.3 dB and 0.4 dB performance gains at the bit error rate (BER) of 10-4 on Gaussian channel and Rayleigh fading channel, respectively.