A kind of differential chaos keying communication system was presented based on repeated chaotic spreading sequence(RCSS). Bit error rate(BER) performance is theortically analyzed and then verified with numerical simulations. In the system, a repeated chaotic spreading sequence is produced by copying the reference sequence of the DCSK-modulated signal, and part of the parallel bit streams are multipled with this RSS. The resulting signals are then conveyed into the channel. Theoretical analysis and simulation results show that BER performance of the system is better than DCSK, CDSK and CD-DCSK. The system performs better as the spreading factor reduces. BER performance over an AWGN channel is better than aht over a Rayleigh channel.