The combined hybrid nite element method for plate bending problems allows arbitrary combinations f de ection interpolation and bending moment approximations. A novel expression of the approach discloses the energy-adjustable mechanism of the hybrid variational principle to enhance accuracy and stability of displacement-based nite element models. For a given displacement approximation, appropriate choices of the bending moment mode and the combination parameter ∈(0; 1) can lead to accurate energy approximation which generally yields numerically high accuracy of the displacement and bending moment approximations. By virtue of this mechanism, improvement of Zienkiewicz' s triangular plate-element is discussed. The de ection is approximated by Zienkiewicz incomplete cubic interpolation. And three kinds of bending moments approximations are considered: a 3-parameter constant mode, a 5-parameter incomplete linear mode, and a 9-parameter linear mode. Since the parameters of the assumed bending moments modes can be eliminated at an element level, the computational cost of the combined hybrid counterparts of Zienkiewicz' s triangle are as same as that of Zienkiewicz' s triangle. Numerical experiments show that the combined hybrid versions can attain high accuracy at coarse meshes.