Abstract: In order to investigate the equivalent modulus of elasticity for the transverse reinforced core material，the Mori-Tanaka method，based on the Eshelby theory，is first applied to obtain the equivalent modulus of elasticity of the core material embedded in a composite sandwich plate. The numerical simulation is then conducted via the ANSYS code package to obtain the equivalent modulus of elasticity for a unit cell， and the simulation results are compared with those calculated with the Mori-Tanaka method，which reveals a difference less than 5%. On this premise，further research is conducted to investigate the effects of variable Young modulus and related matrix sizes on the equivalent modulus of elasticity of the composite core material. The results indicate that the transverse effective elastic Young modulus and in-plane Poisson ratio can be easily affected by changing parameters，yet less influence is observed for the in-plane Young modulus and the transverse Poisson ratio.