Abstract: Polymer materials find wide applications in various fields such as superconducting technology, aerospace, electronic circuits, power batteries, heat exchangers, among others. With the increasing demands for miniaturization, densification, and high power of devices, the overall heat dissipation requirements have escalated. However, polymers, serving as crucial materials in device encapsulation and bonding processes, exhibit a low thermal conductivity of only 0.2 W/(m∙K), which falls significantly short of current heat dissipation needs. Therefore, there is an urgent need to enhance the thermal conductivity of polymers. Constructing continuous thermal pathways within the polymer matrix has been shown to significantly improve the thermal conductivity, often increasing it several times or even tens of times. Hence, utilizing three-dimensional network fillers to reinforce the thermal conductivity of polymers stands out as one of the most commonly employed methods. Accordingly, this paper organizes relevant studies on enhancing the thermal conductivity of polymeric materials through the construction of three-dimensional network fillers. Based on different preparation methods, these are categorized into self-assembly, phase-separation, template-methods, oriented-distribution methods, among others. Finally, a summary analysis is provided from aspects such as the increase in thermal conductivity values due to preparation methods, feasibility, stability, and prospects for the future development of polymer-based thermally conductive composites reinforced by three-dimensional network fillers.