The electronic properties of the ZNWs (ZnO nanowire) as one of important part of novel SC (solar cells) are very important, which can greatly affect the performance of the SC. Based on the density function theory combined with the plane-wave ultra soft pseudo-potential method, the structures, the adsorption energies and the electronic structures of the C2H6O (ethanol), C6H5FS (4-fluoro-benzenethiol), C7HF7FS (2, 3, 5, 6- tetrafluoro-4-(trifluoromethyl) benzenethiol) clusters adsorbed (0001) hexangular ZNWs are calculated. Firstly, the most stable configuration is found out from different adsorbed ones based on the principle of lowest energy by calculating their total energy. The results also indicate that C7HF7FS adsorption is energetically favorable. Then, the densities of state and the electronic structures of different adsorbed systems are calculated. Furthermore, the mechanism for adjusting the band-gap of the absorbed system is investigated and the results indicate that the chemical modification of ZNWs with the small molecule groups results in little change in the electronic property of the system. Meanwhile, charge transfer takes place to a certain extent between the C7H7FS and C6H5FS.