In the paper, undoped and Pr2O3 doped TiO2 nanoparticles were prepared by a sol-gel process using Ti(OC4H9)4 as raw material and characterized by means of XRD TG-DTA, AFM, UV-Vis and FTIR. The photocatalytic activity of Pr2O3/TiO2 was evaluated by the photocatalytic degradation of acidic fuchsine. The factors affecting on photocatalytic activity of Pr2O3/TiO2, such as the content of doped Pr2O3, the calcined temperature and added amount of the catalyst etc. were discussed. It was shown that Pr doping hampers the transformation of TiO2 crystal phase from anatase to rutile, and with Pr2O3 doping the particle diameter of Pr2O3/TiO2 samples decreased, the specific surface area increased and the photocatalytic activity improved. When doping amount of Pr is 0.8%, added amount of the catalyst is 0.03 g and the calcination temperature is 500 degrees C, the degradation efficiency of acidic fuchsine reaches 97%. The photocatalytic degradation of acidic fuchsine by Pr2O3/TiO2 is a quasi-first order dynamic reaction.