Abstract: Based on the modified Hu-Washizu principle for shallow shells, two kinds of generalized compatibility conditions (compatibility condition between adjacent elements and that between membrane strains and displacements) are introduced to reduce the modifiedfunctional to the simple functional of the principle of potential energy. A curved rectangularelement of shallow shell with twenty degrees of freedom is constructed. This elementcan be used in the analysis of both thin and thick shallow shells. Shear locking and membrane locking are avoided.