Bi2Fe4O9 ( BFO) is one of the most important photocatalyst materials and its composition with graphene may leave an optimizing effect on the photocatalytic performance. In this paper, reduced graphene oxide ( RGO) with various contents is selected to be composited with BFO successfully via one-step hydrothermal method. A series of BFO- x RGO ( x=0, 1.25, 2.50, 3.75, 5, 6.25, and 7.50 wt.%) were prepared and the effects of RGO content on crystalline, light absorption, impedance, and photocatalytic degradation rate of methyl violet ( MV) solution are characterized. The entire film samples exhibit enhanced photocatalytic efficiency. Especially, with 5 wt.% RGO content added, the film sample shows the best photocatalytic degradation efficiency with a MV solution degradation rate of 95%. This implies that the composition of RGO allows BFO-based thin film as an efficient photocatalyst candidate, and as well, the BFO/ RGO composite possesses the potential for better use in the related photocatalyst applications. [ABSTRACT FROM AUTHOR]