In high power excimer laser system, the shape of output laser beam from whole system is mainly determined by the front-end of laser beam, and is closely correlated to the requirement of target physics. The experimental development of the front-end laser beam shape control based on a short pulse excimer laser is described. A partial coherence scattering source satisfying requirement of system construction has been developed, and the top-hat laser shaping pulse by three pulses stacking has been obtained. Also, analysis on above methods combining experimental results is given