Pr doped rare-earth orthoferrites DyFeO3 is synthesized by solid state reaction. X-ray diffraction shows that the lattice parameters of Dy1-xPrxFeO3increase and distortion of lattice decreases with Pr content x increasing. Raman spectroscopy reveals that the change of effective mass (meff) meff=xmPr+(1-x)mDy together with lattice structure change results in the shift of vibration modes. With the increase of Pr content, Raman modes of wave number less than 200 cm-1 remain constant, but the modes of wave number greater than 200 cm-1 decrease with Pr content increasing (except the mode B3u near 420 cm-1). The weak ferromagnetic ordering, created by Dzyaloshinsky-Moriya interaction, is reduced with doping level increasing. The interaction of rare earth ions with Fe3+ ion, together with the change of lattice distortion, results in the increasing of spin reorientation phase transition temperature when xx increasing to over 0.3.