Digital manufacturing technology innovates the production system in the various industries. Shipbuilding industry also obtains the improvement productivity and the cost reduction. This paper aims to optimize the schedule planning of shipbuilding assembly process. In this paper the facilities and production process of panel line were modeled in the virtual environment. The variations of production simulation were investigated by changing the capacity of the facilities and the order of manufacturing process in the digital shop. The Simulator of Discrete Event base was developed with the tool and general development language. The simulation results gave the detailed analysis of the given schedule such as work time and productivity at every stage, bottle neck stage, etc. The optimized schedule was found by comparing the simulated result for the various cases. Applies this simulation model and it will be able to confirm the exception and the alternative plan of flow. Also when change investigation of equipment plan and understanding the whole situation of line in the management of a corporation, it will be able to apply a simulation. This paper also showed the web-based user interface to use the developed simulator easily.