The invention discloses an automatic detection method of benzophenone and 4-methylbenzophenone in electronic cigarette liquid. The automatic detection method is characterized by directing by combiningpretreatment automation of an electronic cigarette sample with online gas chromatography-mass spectrum, i.e., directly putting the electronic cigarette sample in a chromatographic bottle, then setting the adding amounts of water, dichloromethane and internal standard, automatically adding by an instrument, carrying out volution, and online detecting the dichloromethane in the lower layer in a gaschromatography-mass spectrometer. Compared with an existing detection method, the automatic detection method disclosed by the invention has the technical advantages that 1, a whole process of samplepretreatment and sampling is in automatic operation, the difference and the accuracy error which are generated while the sample is manually treated are reduced, the repeatability is high, and generalsurvey analysis results are reliable; consumption of a solvent and the sample is less, and the automatic detection method is more environment-friendly; the automatic detection method is fast and efficient and is suitable for general survey analysis of large-batch products, and 150 samples can be treated and analyzed at a time; 2, inaccuracy of a target object determination result caused by solventvolatilization before conventional off-line detection is avoided, sampling is immediately carried out after pretreatment of each sample, and a determination result is accurate and reliable.