Effective thermal conductivity models for nanosheet-based composites are less common than those for composites containing spherical nanoparticle. A novel theoretical model for effective thermal conductivity is proposed aiming to the sheet-like nanoparticle polymer composites in this paper, and comparative analysis is made with other relevant models as well as experimental data. The effective thermal conductivity of the anisotropic nanoparticle is obtained by analysing the differential equations of a sheet-like nanoparticle with an interphase layer in both in-plane and through-plane directions in a cylindrical coordinate system. Then the present model is established based on the Nan's model and the solutions of these differential equations. The present model which contains the effects of detailed geometry and anisotropy of nanosheet as well as interphase layer are analysed and validated with other models and experimental data. The results of present model are in good agreement with some available experimental results.