It is well known that most of mission critical systems like defense systems demand higher quality than general software systems. In order to assure the high quality of the systems, those software systems must be thoroughly tested with well defined testing processes. As software systems evolve, software testing should also be improved with continual-base. Even if there are some previous researches on test process model, those models have some limitations and problems to be applied for software testing process improvement in a specific domain like military weapon systems. In this paper, we propose a new testing maturity model, called MND-TMM(Ministry of National Defense-Testing Maturity Model), which can be adopted effectively for the weapon software system development. We also present OWL ontology for the MND-TMM, called MTO(MND-TMM Ontology) to help software organizations set up their effective testing strategies and improve their testing processes, which can lead to high quality product developments.