In this paper, a passively Q-switched pulsed Nd:YAG laser system is designed and realized for defense applications. Our previously published generalized mathematical model for passively Q-switched lasers is used to help extract the design parameters of the proposed Q-switched Nd:YAG laser system. The proposed laser system is a simple and compact laser source which can be employed for many applications. The laser system operates at 1064 nm, its free running output energy is 150 mJ, while its Q-switched laser output contains a train of pulses with pulse width varies from 47 nm to 85 nm and with maximum measured total output energy of 52.4 mJ. The output pulse series contains 6 pulses with maximum peak power of 468 kW, while the minimum obtained peak power is 18.8 kW. The total duration of the Q-switched output pulse series is about 150 μs. This system can be used in many applications such as Laser-induced breakdown spectroscopy (LIBS), LIDAR, laser target designation (LTD), range finding, and some medical applications.