The detonation wave theory was applied to analyze the interacting process of detonation waves after the shaped charge was initiated with three initiation points. And the forming process and mechanism of the hyper pressure on the symmetrical plane were obtained. The energy sources forming the EFP tails were found. The software of LS-DYNA was simulated the impacting process of detonation waves, the formation of hyper-pressure,and the deforming process of the liner. Results of simulations show the liner overturns and deforms under the action of the nonuniform loads of explosive and three pressure marks on the surface of liner are forged by hyper pressure. The displacement-time curves indicate the formation of the EFP tails is attributed to the different displacements of elements of the liner under the action of the nonuniform loads. The initiation radius has great effect on the slenderness ratio, speed, kinetic energy and shape of tails of the EFP. The appropriate initiation radius was primarily fixed on 20 mm to 30 mm. The experimental result shows a good agreement with results of theoretical analysis and numerical simulations.