Biomass graphene/LaFeO3 nanocomposites (graphene doping amount is 1%, 3%, 5% and 7% of LaFeO3) were prepared by two-step method. In order to obtain phase and microtopography, the biomass graphene/LaFeO3 nanocomposites were characterized by DTA-TG, XRD and SEM. Infrared analysis of samples was carried out by Fourier transform infrared spectrometer (FTIR). Effect of addition amount of the biomass graphene for the graphene/LaFeO3 nanocomposites on the photocatalytic activity in the methylene blue were studied. The results show that the biomass graphene/LaFeO3 nanophotocatalysts by two-step method have good stability and high efficiency photocatalytic activity. Addition of biomass graphene has improved photodegradation rate of LaFeO3 on the methylene blue. The optimal doping amount of the graphene is 7% and the photodegradation rate irradiated for 30 min reaches 56% under 175 W high pressure mercury lamp, which is 50% higher than LaFeO3 as the catalyst.