Under the increasing demand for missile performance, multidisciplinary optimization design has become a key technology in the missile design procedure. In the literature, the guidance and control system design methods are mainly based on disciplinary-specific or simplified models, and cannot describe the interactions between disciplines and their effect on system dynamics. Therefore, this article introduces a multidisciplinary modeling framework to simulate the multi-domain missile system for missile guidance and control system design. The framework is based on Modelica, an object-oriented modeling language supporting non-causal modeling fashion. Within this framework, an air-to-surface missile model is established, and the corresponding trajectory optimization problem is solved using the IPOPT optimization toolbox. The proposed modeling framework provides a versatile missile modeling method for trajectory optimization and design verification, improving the efficiency of the missile guidance and control system design.