Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in environments, and some of them are causative agents of human cancer. Previous studies concluded that benzo[a]pyrene-7,8-dione (BPQ), which is one kind of carcinogenic PAH metabolites, forms covalently bonded adducts with DNA, and the major adduct formed is a deoxyguanosine adduct. In this work, we investigate the interactions between BPQ and DNA molecules via first-principles calculations. We identify six possible DNA adducts with BPQ. In addition to the four adducts forming covalent bonds, there are two adducts bound purely by van der Waals (vdW) interactions. Remarkably, the two vdW-bound adducts have comparable, if not larger, binding energies as the covalent adducts. The results may help us gain more understanding of the interactions between PAH metabolites and DNA.