Highlights: Brazil's economy is very dependent on ports, which serve as the entry and exit of goods via cargo imports and exports. The use of containers has made handling operations in ports easier, increasing the speed of transport and efficiency of the handling process. Because of this, containerization is an innovation in general cargo services, bringing increases in company sites and building large terminals specializing in container handling. However, the internal handling of import containers entails operational costs for the port terminals. To apply a mathematical model to optimize the unloading of import containers, to define the optimal fleet for the process of the company under study. The purpose of the research is described as diagnostic research. As for the type of research, the study is classified as qualitative research. In terms of design, the research is a case study. The analysis technique consists of using in-process modelling and simulation. Modelling and simulation are used in a port logistics context. Through simulation, the number of trucks carrying out transportation was adjusted, demonstrating the ideal amount of vehicles for the terminal's demand. As a result, it was observed that operational research can help in the adjustment of the company's process. This study presents as a limitation the simulation with other equipment that involves the unloading process of import containers, limiting itself only to yard tractors. It is suggested to increase the number of pieces of equipment that involve the unloading process, such as gantry cranes, to verify if there is a decrease in the unloading process time of import containers. To demonstrate that simulation can serve as a tool that helps decision-makers, as well as, be applied in a port process.