A line beam shaping system is developed for low temperature poly-silicon preparation with excimer laser. A spot conversion module is installed to make the beam cross sections of horizontal axis and vertical axis exchange their position. A beam expanding module is used for collimating the short axis of the initial beam, and its magnification determines the spot size of the short axis to match the aperture of the short axis beam homogenizer. The beam homogenizers for long and short axes based on lens array are used to improve the homogeneity of the spot energy distribution and restrict the spot size. A projector is installed to project the beam to the work piece. In order to realize precision positioning of the optical elements, a mechanical adjusting structure is designed and manufactured. The effects of the center error of the lens array unit and the deviation of the working plane on the line beam quality are discussed based on the simulation. The line beam shaping system is used for shaping a homemade high-power excimer laser, and the results show that the measured energy transfer efficiency of the system is 33%, the spot size on the work piece is 100 mm×0.3 mm with the average energy density of 470 mJ·cm-2, and the energy distribution homogeneity of long axis is 93.95%. These results can meet the requirement of annealing technology.