Accurate prediction of effective properties of composites prevents catastrophic failure of components designed, which depends on the non-similarities such as voids, debond, cracks and fibre orientation. Prediction of effective properties of composites with the inclusion of non-similarities in composites by micromechanics approach is prohibitively expensive; Homogenization (macro-mechanics) approach solves the problem by reducing computational capabilities. In this study, finite element models are presented for predicting effective thermal conductivities of a partially debonded unidirectional square-packed array composite. Partial debond angle effect and its location effect are studied. Also applicability of Homogenization approach is tested for three different cases and is found that maximum error between macro- and micro-mechanics approaches (homogenization) is 2.1 %. Effective longitudinal thermal conductivity of the composite is not affected by partial debond.