There are many studies about foundry process design, foundry quality control, and foundry methods selection; however few researches have been published regarding foundry production scheduling management and expert system and flask management in casting production in particular. It is difficult for a production planner to judge whether there are enough flasks to meet the moulding plan in casting companies, and it is a highly troublesome problem to provide the planned castings with the compatible flasks as well. In order to address these two issues, in this paper we analyzes the cause of the problem and finds that the difficulty is to manage assembling flasks, and then constructs a decision analysis method. The method can make a validity analysis to the made moulding plan, and make up a flask assignment solution for the valid plan. Finally, a foundry moulding plan expert system based on the method is developed to prove this study.