Modeling languages, modeling methods, and modeling tools are recognized as the three key elements of Model-Based Systems Engineering (MBSE). Effectiveness in system design and modeling processes relies on their harmonious matching with each other. Object-Process Language (OPL) is a simple yet powerful conceptual modeling language. However, when employing OPL for equipment system architecture design and modeling, there remains a deficiency in matching modeling methods tailored specifically to OPL. To tackle this challenge, the paper introduces an architecture design and modeling method named the Mission-Function-Physical Method (MFPM). This method aims to fulfill the requirements of information-intensive and complex equipment system architecture design and modeling. It leverages various commonly used modeling methods, scrutinizes their general principles, rules, and limitations, and integrates them with the epistemological foundation and linguistic characteristics of OPL. This method matched with Object-process language, can take full advantage of its characteristic, and integrate the mission architecture view, function architecture view, and product architecture view into an organic whole which can support architecture design with a formalized model in a graphical and textual equivalent form, avoiding the fragmentation of the three architecture views during the engineering development process, thereby preventing the final product from deviating from mission requirements. Finally, we apply the architecture design and modeling methodology to a scenario involving unmanned aerial vehicle-assisted wildlife conservation missions to validate the effectiveness of MFPM. This method has demonstrated its capability to support forward design and modeling of equipment systems.