Polymer composites having comparable thermal conductivity to stainless steel at room temperature are commercially available nowadays. Metal or carbon fiber and particles are added to base polymers to enhance mechanical and thermal performance. However for polymer composites having high additive concentration, characterizing mechanical and thermal properties of the composite may be a challenging problem due to an-isotropic natural and non-homogeneity. In this paper, a novel thermal property measurement method based on the 3-omega (3ω) is proposed for thermal analysis of polymer composites. Sensitivity and feasible limit of the 3ω method with “boundary mismatch assumption” is analyzed for measurement of polymer composites having broad range of thermal conductivity.