Abstract: The Hamiltonian solution system is generalized to the Reissner-Mindlin thick plate problems. The Hamiltonian dual differential equations for thick plates are derived and the functional expressions of Hamiltonian variational principle are obtained using the variable substitution and multiplier method. Two orthogonality relationships of the thick plate theory are proposed and demonstrated. The Hamiltonian solution system for thick plates provides a new effective tool for the development of analytical solutions and finite element solutions of thick plates.