The increasing competition between the companies forces them to develop the production in a continuous manner in order to maintain the competitiveness in the global market, and became as efficient and effective as possible. This master thesis is conducted at Getrag All Wheel Drive Company which is one of the largest suppliers for transmissions and powertrain systems .This Company has worked actively for long time to improve the production flow at the manufacturing departments by using usual methods. Because of the high complex and intersected flow that the company has, the management intended to adopt another approach that takes dynamic information into consideration, therefore, building a simulation model is the solution, where according to Banks et al (2001) the simulation is a duplication of a real-world process or system and its behaviour as it progress during the time, which is a very useful method to evaluate complex systems, instead of using usual mathematical means used tools. The simulation model created by using Banks et al (2001) simulation methodology, and ExtendSim software help. The resulted model used as a tool that provides great assistance to the decision makers, in order to develop the Conwip system which applied in the manufacturing line under study, and to investigate “What if” scenarios. The result of this study obtained after performing two experiments, where the first experiment gives recommendation regarding the optimal upper bound of the total amount of work that can be used in Conwip system, with the use of sensitivity analysis, and the second experiment analyse the overall all effect on the system after separating the paths of high and low volume products. This project proves the powerful side of using the simulation in situations where it’s too hard or even impossible to improve the performance of a manufacturing line i.e. when large number of variables involved and affecting the system.