A new random concatenated coding schem e based on LDPC code is proposed.For the coding algorithm of the scheme,diffe re nt degrees of variable nodes are protected by different BCH codes with different error correction capabilities.And for the decoding algorithm of this scheme,a joint iterative decoding (JID) meth od is proposed,which takes hard decision to assist soft decision.This scheme is different from the traditional single-leve l type and interleaved type concatenated codes.Its interleaved depth is determined according to the degree of the variable nodes of the LDPC code.So its interleaved manner is random.The simulation results show t hat when bit error ratio (BER) is 10－8,compared with the single-level type concatenated code,RS (255,9) code in ITU-T G.709,RS(255,9)+CSOC (n/k=7/6,J=8) in ITU-T G.975.1and orthogonal concatenated BCH code with 25% overhead,the net coding gain (NCG) of the four-partition random interleaved concatenated code (RICC-4P ) is improved by 0.15dB,3dB,1.5dB and 0.4dB,respectively.The performance im provement is due to the se t-partition protection and the JID algorithm based on the soft decision with ha rd decision assistant.