The test and evaluation(T&E) of weapon systems is a significant activity in the decision-making process of defense acquisition program, providing the data of trade-off analysis, risk reduction and readiness to advance to next phase of development for the decision-maker. Currently, the modeling and simulation(M&S) is being a critical method in the test and evaluation of weapon systems. Therefore in this paper we review the current status of the test and evaluation for the defense acquisition program in Korea, and suggest an application of M&S in the T&E of weapon systems.