Polymer composites of highly effective thermal conductivity (ETC) are commonly used in various industries, for renewable energy systems and Electronic Systems. Owing to the low thermal conductivity (TC) of polymers, inserting particles with ultra-high TC into the polymer matrix makes it possible for polymer composites to possess high ETC. The ETC of polymer composites is determined by several factors, including the particle and matrix properties and microscopic structures. Modelling methods are powerful tools to understand how these factors influence the ETC of polymer composites. Modelling methods can be combined with experimental data and can be used to qualitatively and quantitatively analyse the impact of various factors on the ETC. Moreover, modelling methods can be used as a guide for the choice and design of particle-filled composites for engineering applications. Herein, we review the recent research on ETC models of polymer composites. First, the classical theoretical models of ETC for polymer composites are introduced. Then, novel theoretical and simulation models are described. We focus on the influence of the theoretical models and the simulation models of polymer composites at multiple scales. Finally, we conclude and give an outlook regarding the ETC models of polymer composites. (C) 2017 Elsevier Ltd. All rights reserved.