Various analytical techniques were used to study the molecular composition and structure of heteroatom compounds in Huadian (HD) shale oil. On the basis of the results obtained from gas chromatography-nitrogen chemiluminescence detection and gas chromatography-sulfur chemiluminescence detection, the composition of nitrogen- and sulfur-containing compounds was estimated. Molecular composition and structural information of heteroatom compounds were characterized on the basis of their type (double-bond equivalence (DBE)), class (number of oxygen, nitrogen, and sulfur heteroatoms), and carbon number distribution using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). In the positive-ion ESI FT-ICR MS mode, a total of 14 different basic species were detected for basic nitrogen compounds. N-1 class compounds dominated followed by N1O1 and N-2 class compounds. The DBE value of N1OX compounds having high relative abundance values increased with the increase in the number of oxygen atoms. In the negative-ion ESI FT-ICR MS mode, a total of 12 classes of compounds were detected for neutral nitrogen compounds and acidic compounds of HD shale oil. O-2 class species were dominant, followed by N-1 and O-1 class compounds. N-1 class species with DBE values of 9, 12, and 15 were carbazoles, benzocarbazoles, and dibenzocarbazoles, respectively.