In recent years, acausal modeling languages such as Modelica and VHDL-AMS have been used for model-based development. In this research, a cycle simulation model using an acausal modeling language for predicting the emissions of an internal combustion engine was developed for application to a vehicle simulation model for energy and emissions analysis. In order to develop simulation models with higher versatility and extensibility using an acausal modeling language, it is necessary to design the structure and hierarchy by understanding its rules and constraints. Hence, the modeling method of the engine cycle simulation using the acausal modeling language Modelica for emissions prediction was discussed. Furthermore, nitrogen oxide emissions were calculated using the developed model, and their accuracy was validated by comparison with experimental data on a spark ignition engine.