Abstract: A method for monitoring the real-time production operation is disclosed. The used stage time, the used waiting time, and the theoretical remaining processing time is counted. The allowed stage time, the allowed waiting time, and the allowed slack time is also estimated. The critical stage ratio, the critical waiting ratio, and the critical slack ratio are then calculated by the following equations: critical stage ratio=allowed stage time/used stage time; critical slack ratio=allowed slack time/theoretical remaining processing time; critical waiting ratio=allowed waiting time/used waiting time. Thereafter, the status of the lot in a stage is graded according to its critical ratio of stage, slack, and waiting. Color codes are used to indicate the critical degrees. A stage critical degree report including the WIPs and the color codes is tabled to display all the statuses of the stage.