Abstract: In this paper, a universal method building the 12 d.o.f. rectangular element suitable for analysing both thin and thick plates is derived. When the plate thickness approachesto the limit of thin plates, the element degenerates to the thin plate element auto-matically,so that the shear locking will not appear. By using this method, two 12 d.o.f. locking-free thick plate rectangular elements (LFR1 and LFR2) are constructed.Numerical results show that LFRl and LFR2 elements have the advantages of high accuracy, good convergence, stability and passing Irons' patch test.