Every firm must adjust to the needs of online trade to manage many consumers' contact channels and using an Omnichannel is one such approach. The current study examines an omnichannel system, implementing three different scenarios and developing a system dynamics model. Simultaneously, the effects on cash flow, inventory, delivery time, and distribution costs are evaluated. As a result, the stock-flow curves and the causal model were created. The resulting concept was then tested and put into practice. In order to maximize the usage of the omnichannel system and expand the retailing capacity, three scenarios were created and put through simulation. Finally, the performance of the suggested model was evaluated by merging the first and second situations. According to the findings, a company's inventory is at its lowest point, and its cash flow is at its best when using the omnichannel system alone. The second scenario alone was not implemented since it did not result in what was desired. The third scenario provides the largest cash flow and delivery time values, according to a comparison of the results of the other scenarios. The first scenario is preferable if the company decides to lower the distribution costs at the cash flow expense.