Hexagonal boron nitride (hBN)-filled composites are widely used in electronics for thermal management. In order to enhance the materials heat transport capability, the hBN platelets are expected to be assembled into well-ordered structure. Such structure has been achieved in practice by the magnetic alignment approach. However, this approach is limited to the composites loaded with low volume fraction of platelets (<10%). In this paper, we report the use of combined mechanical and magnetic stimuli to fabricate the well-aligned composites at the volume fraction from 10% to 20%. The platelets in the resulting composites exhibit a high degree of alignment. For instance, in the 10 vol.% composite, the angle of 95.3% of platelets is greater than 450, only 5% of platelets falls into the horizontal direction. Thermal conductivity of the composites was investigated experimentally. It exhibited strong correlation with the platelets alignment. The measured thermal conductivity of 10 vol.% aligned composite is 74% higher than that of unaligned composite. Thermal conductivity were also analyzed by a theoretical model. Thermal boundary resistance (R-b), arising at the platelets-matrix interface, was extracted by fitting the measured thermal conductivity to model prediction. R-b is found to decrease with the increase of alignment degree. This study suggests that assembling the platelets into well-ordered structure can greatly enhance the heat transport capability due to the formation of conductive networks and the reduction of R-b. (C) 2015 Elsevier Ltd. All rights reserved.