Aim at a certain charge diameter and initiation way, the laws of liner curvature radial, the length of the explosive charge, liner thickness and shell thickness four factors affecting the warhead velocity of LEFP are analyzed using explicit finite element program LS-DYNA3D in this paper. Regarding Vx to Vy ratio as index on this basis and combining with characteristic of LEFP,orthogonal design method is applied to analyze the primary secondary relations of four factors, and LEFPs optimized or not are analyzed by contrasting. The results indicate that liner thickness is main influence factor, so an optimum combination of every level of four factors is gained, and the optimized LEFP has excellently forming performance.