Abstract: GC field ionization time-of-flight high-resolution mass spectrometry combining GC separation, field Ionization and time-of-flight high-resolution mass spectrometry (GC-FI-TOF HRMS) was used for detailed analysis of diesel products. Compared with ASTM D2425, samples need not to be pre-separated, and more detailed information can be obtained by this method. For one analysis, we can get the information of the distribution of carbon number and the number of double bonds, rings and heteroatoms of hydrocarbon compounds, the distribution of sulfur-containing and nitrogen-containing hydrocarbon compounds.