Abstract: To obtain high- purity signal molecules secreted by B. subtilis and to explore the effect on the bacteriocin produced by L. paracasei HD1.7, the signal molecules were separated and purified by hollow fiber system and ion exchange chromatography in this study. SDS-PAGE was used to detect the purity and apparent molecular weight of signal molecules. The effect of signal molecules on L. paracasei HD1.7 bacteriocin was analyzed by antibacterial test. The results showed that three elution peaks occurred when pH 4.0 NaAc + NaCl solution was used as eluent, and the antimicrobial activity of L. paracasei HD1.7 added with elution peak P3 was higher than that of the original strain by 11.31%. However, the addition of elution peak P1 and P2 did not increase the antibacterial activity of L. paracasei HD1.7 compared with the original strain. Thus, P3 was the target elution peak containing the signal molecule, and the elution peak P3 was a single band detected by SDSPAGE. The optimal chromatographic condition was: ion exchange chromatography eluent (B eluent) was NaAc+ NaCl solution with pH 4.0, equilibrium eluent (A eluent) was NaAc solution with pH 4.0, the flow rate was 2 mL/min. SDS- PAGE analysis showed that a band appeared with molecule mass about 5 kDa. Subsequent antibacterial tests indicated that B. subtilis signal molecular in the chromatography solution could promote L. paracasei HD1.7 producing barteriocins.