As is reported, the photocatalytic activity will increase significantly when TiO2 nano particles are agglomerated into TiO2 nanofibers (NFs), but the photocatalytic activity enhancement mechanisms are still not fully understood. As is widely accepted, the optical absorption process plays a key role in photocatalysis, and it can even be said that the optical absorption capability of the photocatalyst directly determines its photocatalytic activity, while the influence of the structure on the optical absorption characteristics of TiO2 has largely been ignored in the existing explanations. In this paper, optical simulations are introduced into analyzing optical characteristics of TiO2 Nanofibers with which, the photocatalytic activity enhancement mechanism is further discussed, and a photo catalytic activity enhancement mechanism of TiO2 Nanofibers is proposed. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.