An analytical approach was developed for rectangular platelet reinforced composites which could be used for a 3D elastic stress field distribution subjected to an applied axial load. The ends of the platelet could be bonded to the matrix. Exact displacement solutions were derived for the matrix/platelet fromtheory of elasticity. These displacement solutions were then superposed for achieving analytical expressions for the matrix/platelet 3D stress field components over the entire composite system including the platelet end region, using the adding imaginary fiber technique. The platelet/matrix components could exactly satisfy the equilibrium and compatibility conditions and satisfy the equilibrium requirements and the overall boundary conditions. The obtained analytical results were then validated by FEM and Shear-lag modeling; and some of discrepancies among the shear-lag models were resolved. Good agreements were observed between the analytical and numerical predictions.