The most important role of air defense system is to attack the air target of enemy to defend the important military unit or facilities. In order to attack the target as soon as it is detected, fast and precise fire signal transfer using the fire control stick is very important. However, it was found that firing is not conducted in the test for fire control stick. In order to find the reason of such problem and improve life cycle of fire control stick, the test was conducted and it was found that chattering occurred and this led to malfunction of signal transfer from control stick to fire control unit of air defense system. In order to draw resolution for this problem, two contact plate made of beryllium copper is suggested to add to the control stick to enhance the contact and reduce chattering effect. The four fire switch prototypes were tested for 100,000 times and it showed its reliability of use.