Warehouse is an important distribution centre. Receiving and delivering are the interface of a warehouse for incoming and outgoing material flow. In this work, the processes in the loading (delivering) and unloading systems (receiving) are carried out simultaneously daily at the warehouse. The processes in the unloading system are the arrival of supplier’s lorry, checking, unloading, packing, sealing and storage. On the other hand, arrival of a customer’s lorry, processing the delivery order, order picking, sealing, loading and checking are the processes undertaken in the loading system. In this paper, a simulation study was conducted in order to overcome some of the problems at a warehouse in a factory, especially the waiting times at the various processes. These long waiting and total times mean the drivers will lose the opportunity to serve any other distributor and workers at the warehouse have to work overtime. The management realised that the problem is due to lack of facilities and workers. The facilities at the warehouse include forklift, sealing machine, dock, pallet and computer. Therefore, a simulation study was proposed to model the loading and unloading systems in order to find a strategy that will optimise the residence time of any lorry in the warehouse and overcome the overtime problem. In ARENA, a simulation model can be built by putting together predefined modules, which represents processes or logic. Connector lines are used to connect modules and designate the flow of entities. Statistical data, such as cycle time and waiting time are recorded and displayed automatically as reports by ARENA.