Melamine resin microcapsules encapsulating liquid paraffin as core materials are synthesized. By using melt blending method, different ratios of microcapsules and modified potassium titanate whiskers (PTWs) are added to poly(butylene terephthalate) (PBT) matrix to fabricate the binary and ternary PBT composites. The effect of oil-loaded microcapsules content on mechanical properties and tribological properties of PBT composites are evaluated by electronic universal testing machine and high speed block-on-ring wear tester, respectively. The results indicate that the incorporation of microcapsule could significantly reduce the friction and wear of the composites mainly due to the self-lubricating effect of liquid paraffin released from the ruptured microcapsule during the friction process; however, the mechanical properties of the PBT binary composites are reduced. Hence, PTWs are adopted to effectively improve the mechanical properties of materials which could improve the tribological properties of the ternary composites as well due to the synergistic effects of microcapsules and PTWs. POLYM. ENG. SCI., 59:490-499, 2019. (c) 2018 Society of Plastics Engineers