Cso/g-C3N4 composite was reported experimentally to be of high photocatalytic activity in degrading organics. To investigate the underlying mechanism of high photocatalytic performance, the structural and electronic properties of g-C3N4 monolayers with adsorbing and removing fullerene C-60 are studied by means of density functional theory calculations. After 25 possible configurations examination, it is found that C-60 prefers to stay upon the "junction nitrogen" with the carbon atom of fullerene being nearest to monolayers. Correspondingly, a type-I band alignment appears. Our results further demonstrate that the adsorption of C-60 can lead to an irreversible structure distortion for g-C3N4 from flat to wrinkle, which plays a crucial role in improving photocatalytic performance other than the separation of carriers at interface due to the formation of type-II heterojunctions as previous report. Compared to flat one, the light absorption of wrinkled structure shows augmented, the valence band maximum shifts towards lower position along with a stronger photo-oxidation capability. Interestingly, the results indicate that the energy, light absorption and band edge all have a particular relationship with wrinkle degree. The work presented here can be helpful to understand the mechanism behind the better photocatalytic performance for C-60 modified g-C3N4. (C) 2017 Elsevier B.V. All rights reserved.