Abstract: The paper puts forward configurable parameter of reflective quarter wave-plate at normal incidence with extended boundary condition method due to absent report about reflective quarter wave-plates made of gratings.we find phase difference between TE wave and TM wave can satisfy designed requisition at some accuracy in a long span of groove depth which can reduce practical difficulty of etching groove depth,but papers issued before always require strict etching groove depth.Azimuth problem when lineary polarized light transforms circinal polarized light is discussed at the same time.