After being infected with bacteria, temperate bacteriophages can choose to enter the lysis route or lysogenic route according to different environments. The most classic example is that L bacteriophage infects Escherichia coli, and the pL and pR promoters on L bacteriophage genome determine the fate of its cleavage or cleavage. In recent years, scientists have discovered a new decision-making mechanism in Bacillus subtilis: AimR-AimP-AimX decision-making system. AimP encodes a polypeptide of 43 amino acids, which is secreted into the cell envelope and cut into a mature peptide of 6 amino acids. AimR is the receptor of signal short peptide, and also acts as a transcription regulator to regulate the expression of aimX gene. AimX is a negative regulator of bacteriophage lysogenic pathway. The signal peptide is transported into the cell to combine with AimR, releasing the regulatory effect of AimR on aimX gene, and making the phage enter the lysogenic cycle. This decision system exists widely in different phage types. However, the molecular mechanism of how phage recognizes signal peptide and how signal peptide releases the binding of AimR to DNA is still unclear.