The nonuniformity of the irradiation on the target is eliminated by adjusting the intensity distribution on the cross section of the incident laser beams while keeping the position and direction of the beams that are used for indirect-driven laser fusion unchanged. A simulating program that can calculate the intensity distribution on spherical target with several beams irradiating on it is written. The intensity distribution on the target and its nonuniformity are worked out according to the condition of the incident beams. Then the distribution on the focal plane of the beams is educed by using the principle of weighted average. Finally the laser′s electric field distribution before the lens that is necessary for the uniform irradiation is obtained based on the laser transmission theory.