Complex System Modeling, Simulation and Optimization Language (CoSMSOL) is problem-oriented and designed to run on multi-core computers. This paper provides the system environment of CoSMSOL and proposes the modeling methods of complex system, language text specification, function library, algorithm library, parallel simulation algorithms and intelligent optimization algorithms which support continuous system, discrete system and agent systems. Also, we developed a simulation language compiler of CoSMSOL, which is employed in two case studies generating a multi-entity war gaming system and an aerodynamic spacecraft model. The two cases illustrate main functions and implementation processes of CoSMSOL. The results validate that CoSMSOL is useful to model agent-based system and aerospace system.
