To explore the effects of nonmetal elements mono-doping, the electronic structures of (B, C, P, F) doped InNbO 4 have been investigated systematically based on the first-principles calculations. The obtained results revealed that the band edges of (B, C, P) doped InNbO 4 slightly expanded while the band gap of F doped InNbO 4 barely changed. Meanwhile, different p orbital states were introduced into the band gaps of InNbO 4 after (B, C, P) doping, which was in favor of extending the absorption spectra to the visible-light region. Among these nonmetal doping systems, it was noted that the band edge potentials of InNbO 4 satisfied the requirement for water splitting in C doped InNbO 4 . The localized C 2p states could perform as intermediate levels to reduce the transition energy of photo-induced electrons. Therefore, we put forward that C atom should be a suitable dopant for single anion doping InNbO 4 , which will provide a guideline for developing doping InNbO 4 with visible-light sensitive reactions.