Molecular transformations of heteroatomic compounds during visbreaking of Venezuela Orinoco AR were studied by ultrahigh-resolution negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS). The results indicated that the relative abundance of O2, O1, N1O2, S1, O1S1 and O2S1 are decreased or even disappeared, but those of N1, N2, N2O1, N2S1, N3, N3O1, and N1S2 are increased after the visbreaking. The highest relative abundance is O2 class in Venezuela Orinoco AR, while in the visbreaking product (VB) it is N1. The high abundance O2 class contains the species with double bond equivalents (rings plus double bonds, named DBE) 3 and 4 in the AR, which are 2 or 3 cyclic naphthenic acids. By visbreaking, the relative abundance of O2 class is decreased and carbon number is also reduced, mainly DBE 1~4 compounds. The highest abundance N1 class contains the species with DBE 12 in the AR. After visbreaking, a bimodal DBE distribution around 12 and 15 is observed for the N1 class, suggesting two possible stable core structures. The distribution of carbon number and highly abundance of carbon number distribution is reduced, suggesting that the side-chain cracking reaction is mainly concerned for N1 class compounds.