Conceptual modelling is the process of abstracting a model from a real or proposed system into a conceptual model. An explicit conceptual model representation allows the model to be communicated and analysed by the stakeholders involved in a simulation project. A good representation that can be understood by all stakeholders is especially essential when the project involves different stakeholders. The three commonly used paradigms in business applications are discrete-event simulation, agent-based simulation, and system dynamics. While the conceptual model representations in discrete-event simulation and system dynamics have been dominated by process-flow and stock-and-flow diagrams, respectively, research into the conceptual model representation in agent-based simulation is relatively new. Many existing representation methods for agent-based simulation models are less friendly to business users. This chapter advocates the use of Business Process Model and Notation (BPMN) diagrams for the agent-based simulation conceptual model representation in the context of business applications. This chapter also demonstrates how the proposed BPMN representation and other methods such as Petri Nets, DEVS, and UML are used to represent the well-known SugarScape model.