The invention relates to a method for detecting residual organics on a fire scene based on a surface enhancing raman spectrum. The method comprises the following steps: constructing a detection substrate material which comprises a metal film and a nanometer particle, wherein the surface of the metal film is modified with functional groups, the metal film has a hydrophobic effect and is smooth and flat, and the nanometer particle has surface enhancing raman activity and is free from modification with the functional groups; dropwise adding the filtration liquid onto the surface of the metal film with the hydrophobic effect; after finishing the dropwise adding, naturally volatilizing the liquid; dropwise adding the colloid containing the nanometer particle with the surface enhancing activity on the surface of the metal film and utilizing a raman spectrometer to detect the colloid on the surface of the metal film; comparing and analyzing the acquired spectrum chart and identifying the category of the organic compound in the to-be-detected article. According to the method, the operation is simple and convenient; the detecting base structure is simple and can be directly used for extracting, absorbing and enriching the analyte in the solution sample; the designed and constructed enhancing system can realizably acquire high-quality SERS test result; the method has the advantages of high sensitivity, excellent repeatability, zero background interference, and the like.