By analyzing the complex values of the electromagnetic fields along surface relief gratings for TE polarization, the diffractive properties of surface relief micro-structures are discussed. The edges and walls of the grooves are found to have significant effects on the surface fields for wavelength-size grooves. The dependence of these effects upon several factors, including the complex refractive index of the material, incident angle and the depth of the grooves, is examined. An oscillating property of the surface field amplitude at the bottom of the grooves against the depth is discovered and discussed. The far field intensity is also found to be closely related to the depth of the grooves.