This paper reports a sequential prediction system of "Large scale database-based Online Modeling (LOM)". The sequential prediction system predicts time-series process variables repeating processing that predicts process variables of next step by using the predicted process variables of previous step and prepared manipulated variables. Furthermore, the system is applied to the industrial reactor; Practical effectiveness of the system is verified. As the result, the system has predicted the process variables with satisfactory accuracy. The practical effectiveness has been confirmed.