Much of the success of an organization is focused on making decisions in its operations function. Managing properly the men and machines that intervene in their transformation processes, becomes a real challenge in order to increase effectiveness. For this, the optimization based on discrete event simulation constitutes a tool of great potential, due to the savings implied by its use in terms of time, cost and by its capacity to minimize errors in decision making. The present work was proposed to demonstrate the strengths of these tools as support on decision making, for optimize the assigment of these resources in the productive processes with certain level of complexity and that guarantee a good performance of the system. For that, the FlexSim software was applied as discrete event simulator, together with its Experfit and Experimenter tools; and IBM SPSS Statistics for other statistical analyzes. The results are presented with the application to a case study related to a company producing socks and belonging to the textile sector of Imbabura province, Ecuador. The men and machines assigment is made by each of the sections and subsections that make up the limiting point of the production process, adjusted to the amounts determined in the Master Production Schedule for each type of socks, ensuring minimal total cost and good performance of the principal metrics in that operation.