The success of small and medium enterprises to adapt to constant changes in the environment largely depends on the different strategies and management decisions taken by managers at the operational level. This paper is searching for a tool that would allow managers at all levels to consider the effects of their decisions on the success of the enterprise as a whole. In this sense, the application of system dynamics developed one modular simulation model of business processes of SMEs. Developed model recognizes the specificities of SMEs, such as a large range of products, the use of a wide variety of materials, production in small batches and requests for reduction of lead time (Lead Time). The effects of various strategies and management decisions can be observed by monitoring the dependence of performance measures of simulated process on values of model parameters. Through four experiments the effects of changes in inventory management policies, the availability and size of the lot were simulated. The results of experiments showed that the variation of the model parameters should be oriented simultaneously towards several of the aforementioned directions.