Uniform near-spherical nanoscale silver films (NSFs) as a very sensitive and stable SERS-active substrate were synthesized by a facile and efficient in situ liquid−solid−solid (LSS) reaction method without expensive equipment and harmful reagent assistance. In this method, the in situ formation and thermal decomposition reactions of the Ag− melamine coordination polymer (AgM CP) nanowires was utilized to control the morphology and microstructure of the NSFs. The sensing performances of the synthetic NSFs as SERS substrates were investigated by using R6G as a probe molecule. The research results showed that the prepared NSFs possessed a very low detection limit down to 10 −13 M, a high analytical enhancement factor, and stable detection capabilities for the R6G molecule, which made them promising as cost-effective and highperformance SERS sensing platforms for trace molecular species detection.