Abstract: In order to improve the stress accuracy of thermal elastic composite laminates, the generalized H-R variational principle of elastic material was extended to the generalized H-R variational principle of thermal elastic material based on the symplectic element theory of related references, and the corresponding modified principle was proposed. The parametered symplectic element was established. One of the main advantages of this element is that there is no zeros in the leading diagonal of coefficient matrix compared to the traditional mixed element. Consequently, the stability of the numerical results of finite element linear system of equations is guaranteed. At the same time, the element is symmetric for both the displacement variable and the stress variable, so its corresponding finite element linear system of equations is symmetric and symplectic conservation. Compared with the exact solution, the numerical results show that the accurate order of the generalized displacements and stresses are consistent, and hold high accuracy.