Abstract: The preparation of thermally conductive pads with high vertical thermal conductivity and low compressive stress relaxation is of great significance for improving the vertical heat dissipation capability of current high-power electronic components. In this paper, based on the ice template method, a bottom-up vertically oriented thermal network is designed to achieve high thermal conductivity. First, we use dopamine-modified hydroxylated boron nitride nanosheets and silver nanoparticles (BNNS@PDA/Ag) as hybrid thermally conductive fillers, cellulose nanofibers (Cellulose nanofiber, CNF) are used to prepare composite, and a semiconductor is applied as refrigeration table for the composite’s directional freezing. The frozen samples are freeze-dried to form an aerogel, and then polydimethylsiloxane (PDMS) is vacuum poured into the aerogel to prepare BNNS@PDA/Ag-PDMS thermal pad with high thermal conductivity and low stress relaxation. The results show that the theoretical relaxation time loss decreases first and then increases with the increase of silver nanoparticles (Ag NPs) content. When the aerogel mass fraction reaches 19.7wt%, the theoretical relaxation time of the thermal pad corresponding to 3wt% Ag NPs content reaches 32204 at 20% deformation, the vertical thermal conductivity of thermal pad is up to 3.23 W/(m·K). The ice template method can be used to prepare the vertical packing thermal network with high orientation, which has a good application prospect in the field of thermally conductive pads.