Analytical modeling for heat transfer behavior of micro-nano fiber-reinforced composites to determine the dimensionless effective thermal conductivity in the transverse direction has been performed. A hexagonal unit cell was developed that contained matrix, filler and interface (barrier) as the components. Thermal-electrical analogy method was used in the model. Models were developed with and without barrier effect. Filler ratios were taken to be between 10 and 30 %. Effects of barrier thickness and filler volume fraction on the dimensionless effective transverse thermal conductivity have been analyzed. The Rule of Mixtures and analytical modeling results have been compared. The model showed that increasing the volume fraction of the filler inside the matrix increased the total effective thermal conductivity values. When the barrier thickness increased, the dimensionless effective thermal conductivity value increased. © 2009, SAGE Publications. All rights reserved.