A new scheme is proposed to generate adjustable rectangular hollow beams by wave plates. According to the birefringent property of crystals, the thickness distribution of wave plates is designed. The wave plates can form the four- step phase plate to o light and the π phase plate to e light. The rectangular cross- section hollow beams will be obtained with the vertically irradiate on the surface of the wave plate by linearly polarized light beams. In addition, it is simple optical arrangement and easy adjustment to regulate the ratio of the length and the width of the adjustable rectangular hollow beams by means of the adjustment of the length and width of the light transmission windows. Approximate non- diffracted rectangular hollow beams will be obtained through the optical system consisting of the long focal length lens group and a conical surface prism focus diffracted light.‘Hollow bread’beams with the rectangular section will be obtained through the focusing of the high numerical aperture lens.