The pultrusion process allows the production of continuous fiber-reinforced products. Today, fiber-reinforced plastic composites with a thermoset matrix can be produced very well. Also in terms of sustainability, new developments require increasing demands on lightweight construction. So the process research for the production of continuous fiber reinforced, thermoplastic components is of high interest. However, this requires the development of a new process, the so-called In-Situ-Pultrusion, in which low viscous monomers of a thermoplast polymerize in the mold. The high novelty-degree of the process is accompanied by a large number of influencing factors, which can be analyzed experimentally. However, this takes a lot of time and resources, as the optimization of the process is associated with many iteration loops. In order to develop the process more efficiently, this paper presents a simulation approach that maps the motion of the fibers, the fiber-fluid interaction and the polymerization reaction. The simulation model will be implemented in OpenFOAM. Input parameters for the simulation and empirical equations describing the reaction kinetics are determined experimentally and are implemented in the simulation model. Subsequently, the existing pultrusion die at Institut für Kunststofftechnik is modeled and CFD-simulations are performed. The temperature profile is compared with experimental results.