Inspired by the importance of charged nano-particles (NPs) in biomedicine and their potential applications in nanofluids, we analyze the translocation of cationic and anionic nanoparticles through a nanochannel by explicit solvent molecular dynamics simulations. We focus on the interplay of NPs and ions. The cations bind to the anionic NPs much more than the anions to the cationic NPs, which in turn affects the flux behavior. In particular, the nanochannel enhances the difference between cationic and anionic NPs during the translocation process. With the increase of salt concentration, the ion flux increases nonlinearly with external field strength, in agreement with recent experimental observations, while the NP flux decreases, which suggests a nontrivial competition between the translocation of ions and NPs. Our results revealed the important role of ions during the NP translocation and may have implications in the detection, separation, and filtration of charged NPs.