Polycyclic aromatic hydrocarbons (PAHs) residues in the environment seriously harm the human body. In this paper, a colorimetric and SERS dual-channel sensing detection of pyrene in water based on AgNPs-AuNPs was designed. Firstly, single-mercapto β-cyclodextrin was modified onto the surface of gold and silver nanoparticles. When Ox-TMB was present in the system, the nanoparticles would self-assemble to form an AgNPs-Pyrene-AuNPs core-satellite structure triggered by pyrene. On the one hand, pyrene acted as a molecular bridge, causing a certain aggregation of nanoparticles. Moreover, the concentrations of pyrene directly affected the solution color by the core-satellite structures of AgNPs-pyrene-AuNPs. Therefore, the relationship between solution color and pyrene concentrations can be established by visual inspection. On the other hand, there were many “hot spots” in the core-satellite structures, and they exhibited strong surface-to-enhanced Raman spectroscopy (SERS) activity, which can realize the highly sensitive and specific detection of pyrene molecules by SERS. Based on this structure, the highly sensitive and specific detection of pyrene in water and soil can be realized by colorimetric and SERS method. This method could quickly complete the detection of trace pyrene in 5 minutes. The detection limit of pyrene by colorimetric method was, and that of the SERS method was. According to the principles above, SERS sensors based on AgNPs-PAHs-AuNPs core-satellite structure can be used to detect multiple PAHs in water samples. Therefore, this dual-channel sensing system provides a new method for detecting PAHs in water and provides a new idea for the development of a multiplexing sensing system.