Focusing on the issue that the noise influences transmission of symbol in the digital communication system, to improve system reliability and reduce Bit Error Rate (BER) of the received signal, a new Stochastic Resonance (SR) system based on the optimal match and parallel array theory was proposed. Firstly, the parallel array theory was used to improve the stochastic resonance effect of single bistable system. Secondly, the method of optimal match for SR was also used in array systems for weak signal detection. Finally, an analytical expression of the Signal-to-Noise Ratio (SNR) gain in the optimal matching stochastic resonance bistable system was derived; furthermore, the influence of array number on the BER was analyzed. In the comparison experiments with single stochastic resonance system, the performance of the optimal matching array stochastic resonance system on the detection of weak signal in strong noise background was improved, the SNR gain of the output signal of the system was significantly higher than 1, and the BER was also significantly reduced; in addition, SR performed better while the number of units of stochastic resonance system increased. The theoretical analysis and simulation results show that the optimal matching array stochastic resonance system can effectively improve the reliability of the digital communication system in practical engineering.