Based on the knowledge of the analytical approach for production queue model, simulation technology, with using Flexsim, has been widely developed and applied in various manufacturing enterprises to achieve lower production costs and improve production efficiency. Flexsim can be modeled in many different ways to illustrate the layout and the working condition of production lines. In the thesis, researches on production line including methods, optimization and application on Flexsim are briefly introduced. After presenting the concepts of variability, randomness and the production line are discussed in the analytical approach of queue model with application to the queue theory, the modeling tool, Flexsim, which the functions and workable components with the specific operation steps based on simulation software are simply introduced and developed.