A multi arm Michelson interferometric system for the shaping of the nanosecond laser pulse is designed. Process of the pulse shaping by an all optical method is analyzed theoretically. According to a specially designed pulse shape for the purpose of ICF targeting usage, parameters of the system are calculated. In conclusion, when the width of the shaped laser pulse is in the range from 2 times to 4 times the width of the primary input pulse, the pulse shaping system works well.