Oil-impregnated monomer casting (OMC) nylon composites reinforced by graphene oxide and Lanthanum(III) chloride (LaCl3) were prepared by anionic ring-opening polymerization in the presence of sodium hydroxide catalyst and toluene-2, 4-diisocyanate cocatalyst. The cross-linked GO was formed by the coordination and electrostatic interactions between La3+ and the carboxyl on the edge of GO, which resulted in an obvious reinforcement for the OMC nylon composites. The effects of different rare earth contents on mechanical and tribological properties of the composites were carried out. The results showed that the composites exhibited excellent comprehensive properties when 0.01 wt% GO and 0.007 wt% LaCl3 were incorporated in OMC nylon. The elastic modulus, flexural strength, flexural modulus, compressive strength, notched impact strength, and elongation-at-break for the OMC nylon/GO/LaCl3 composites increased by 6.1, 9.9, 18.2, 7.2, 40.8, and 24.4%, respectively, and the tensile strength was slightly improved. In addition, the abrasion quantity was reduced. POLYM. ENG. SCI., 59:982-988, 2019. (c) 2019 Society of Plastics Engineers