To improve the efficiency of weapon design and manufacturing, the calculating program for missile system parameters is written based on the GUI of MATLAB, the system concepts have been analyzed and the arithmetic has been designed in 6 modules, which are warhead design, guiding and control analyzing, speed scheme, dynamical scheme, mass scheme and the position arrangement. Finally, the collectivity of an Antitank Missile is formed and the infection of Tacticstechnical targets changing to the system parameters is studied. The results indicate that this method is a fast way to design an Antitank Missile, analyzing the system parameters and to make suggestions to that as well.