This thesis encounter with the evaluation and estimation of thermal conductivity of “Epoxy Composites Embedded” when filled with boron nitride (BN). These composites with BN content ranging from 0 to 11.3 vol.% have been prepared and the thermal conductivities of the samples are measured experimentally. A numerical simulation using finite element package ANSYS is used to explain heat transfer process within epoxy matrix filled with micro-BN and the effective thermal conductivity values obtained from this method are validated with experimental results and theoretical correlation. It is observed that for 11.3 vol% of micro-BN in epoxy matrix, the increase in thermal conductivity is about 27.82 % while for 30 vol% the increase in thermal conductivity is about 440 % which is reasonably higher compared to neat epoxy resin. The results show that the BN particles show a percolation behaviour at 20 vol% at which a sudden jump in thermal conductivity is noticed.