(PrNd)14-xMMxFe80.4B5.6 permanent magnet materials were prepared from mixed rare earth (MM) of Bayan obo. 30% of PrNd alloy was replaced by MM. The material exhibits a remanence of 1.18 T, a maximum energy product 238.08 kJ/m3, and an intrinsic coercivity of remanence 726.75 kA/m. Oxide of La and Ce exists in rich rare earth phase and there are (NdCe)2Fe14B and (NdLa)2Fe14B in main phase. Compared with others magnets, La content in (PrNd)14-xMMxFe80.4B5.6 magnet is higher when getting the similar magnetic performance. La, Ce, Pr and Nd in the mixed rare earth magnet act together, so MM is used efficiently. Domain structure change was observed by high field Kerr microscopy. The domain wall could be through the grain boundary, and the magnetic domain is easy to spread under magnetic field.