In this study, we attempted to regulate the intermolecular distance of PNTP molecules on the surface of silver foil by breaking the S-S bond of NPDS. Though changing the laser wavelength and power, SERS conditions, the Raman spectra of NPDS and PNTP with different concentrations were compared. We found that, under SERS conditions, NPDS converted more efficiently than PNTP to DMAB at low-concentration with low-power and low-energy irradiation. The results indicate that the distance between molecules plays a significant role in the reaction of PNTP to form DMAB.