A new beam-shaping method for high-power LD bar is presented. In this method, firstly beams are separated into several layers along fast axis direction, and then they are rearranged along slow axis direction,finally a high brightness rectangular beam is received at the output. The principles and shaping mechanism of the shaping element are discussed in detail. The spot size of the output beam is calculated by using the geometrical optics method. The output beam quality is evaluated. Numerical results show that the beam quality has been improved significantly.