An interposer model based on ordered metal microstructure reinforced polymer composite was established using ANSYS software. The shape of metal microstructure includes quadrilateral, hexagon and triangle. The stiffness and thermal conductivity of composite interposer was calculated and discussed. Simulation results show that the stiffness of the metal microstructure-reinforced polymer composite interposer increases with augmenting the volume fraction of metal compared with the pure polymer. For the composite with metal volume fraction of 65%, the stiffness of the triangular composite interposer is 3.12 times that of the pure polymer interposer. The thermal conductivity of the hexagonal model is the best, while the one of quadrilateral and triangular model is similar. For the composite with the metal volume fraction of 65%, the thermal conductivity of the triangular composite interposer is 3.42 times that of the pure polymer interposer. Therefore, metal microstructure can effectively improve the performance of the pure polymer interposer.