Purpose <p>The purpose of this study is to develop a new quadrilateral four-node finite element based on a strain-based Trigonometric Shear Deformation Plate Theory (TrSDPT) for the static and free vibration analysis of laminated composite plates, while achieving high accuracy with a reduced number of degrees of freedom.</p> Methods <p>A novel strain-based finite element formulation is proposed using a trigonometric shear deformation theory with a sinusoidal transverse shear strain distribution that satisfies the zero transverse shear stress conditions at the top and bottom plate surfaces. The element employs five degrees of freedom per node and completely avoids the use of shear correction factors. Membrane and bending strain components are consistently combined within the strain-based framework to improve numerical accuracy and efficiency.</p> Results and Conclusions <p>Numerical studies are performed on symmetric and antisymmetric laminated composite plates with various geometries and boundary conditions. The results demonstrate displacement errors below 2% and natural frequency deviations within 1.5% compared with reference solutions, confirming the excellent accuracy, stability, and computational efficiency of the proposed finite element.</p>