Abstract: In this paper the orthogonal and ortho-laid space gridsare assumed as an orthotropic sandwich plate, which is analyzed by thetheory of plate with consideration of shear deformation and threegeneralized displacements. The calculating formulas for internal forces anddisplacements of double-layer space grids under local loading are given based upon ESPM, andhave been validated by the finite element method (ANSYS). In general, the differences between ESPM and FEM are lessthan 10\% and 5\% for internal forces and displacements, respectively.So this method can be used in the design of double-layerspace grids.