The present invention provides a method for determining hydrogen sulfide (H2S) by headspace single-drop liquid phase microextraction and intelligent device colorimetry, which comprises: taking a silver-gold core-shell triangular nanosheet (Ag@Au TNS) as a nanodetection probe, in combination with an analysis method of headspace single-drop microextraction (HS-SDME), specifically extracting H2S volatilized from a sample to be detected by the nanodetection probe, and detecting H2S in the extracted sample with the help of the photographing function of an intelligent device and a color picking software. Compared with the prior art, the present invention adopts intelligent device colorimetry, with the limit of detection of about 65 nM and the linear range of 0.1-100 μM, and the established method can be applied to the determination of H2S in actual samples such as egg white, milk and other opaque samples, and has the advantages of few procedures, simple operation, high detection efficiency and the like.