Because of the problem about long burst error which is caused by turbulence in atmospheric optical communication, a scheme of low-density parity-check (LDPC) code with channel interleaving is investigated. Taking the interleaving distance as fitness function, a design method of interleaver based on genetic algorithm is put forward. According to the analysis of the distance property about some interleavers, the new interleaver has obvious advantages compared with the block interleaver,the random interleaver and the chaotic interleaver.The simulation results show that compared with the random interleaver and the chaotic interleaver ,the interleaver based on genetic algorithm at bit error rate (BER) of 10-5 have more gain 0.5 dB and 0.87 dB under weak turbulence, respectively. Above all,the new design scheme of interleaver will have certain utility in atmospheric optical communication.