We demonstrate the possible use of organometallic nanoprobe on competitive surface-enhanced Raman scattering immunoassay for policyclic aromatic hydrocarbon detection in sea water. This type of SERS immunoassay is based on to capture Raman reporter-labeled immuno-Au onto the immobilized layer of antigens (benzo[a]pyrene) on the gold substrate after incubation of these nanoprobes with PAHs including in the sample. To realize nanoprobes, first we have prepared gold nanoparticles (GNPs) according to Frens’ method. Then, we have labeled GNPs by the Raman reporter of 5,5’-Dithiobis(succinimidyl-2-nitrobenzoate) (DSNB). Thereafter, Benzo[a]pyrene antibody was attached to the DSNB labeled GNPs. Before use in SERS detection, their activity was controlled by surface plasmon resonance. The present method allows us to detect benzo [a]pyren at traces concentration (ppb). The results demonstrate that the proposed method has the wide potential applications in the investigation of PAH pollutions of sea water (Figure).