Abstract: The tribological properties of La2O3 particles prepared under the conditions of different calcination temperatures and times were investigated. La2O3 particles were modified by oleic acid before use. The point and surface contact antifriction and antiwear properties of modified La2O3 particles in 400SN base oil were investigated. The worn surfaces were analyzed by SEM and EDX techniques. Results indicate that La2O3 particles calcined at 700 ℃ have good comprehensive tribological properties. The longer the calcination time, the better the crystal structure of La2O3 particle. The modification of oleic acid improves the dispersion of La2O3 particle in the oil. Compared the 400SN base oil without modified La2O3 particles, the point contact antifriction of the oil with modified particles increases by 10.8%，antiwear increases by 27.8%, meanwhile, in the case of surface contact，the antifriction performance increases by 16.9%.