In the field of pig ironmaking process, operation malfunction is caused by both enlarging a blast furnace and increasing use of low quality ore. Thus, operation support systems predicting a blast furnace performance are demanded. This paper reports a Java-based operation support system integrated with a "Large-scale database-based Online Modeling (LOM)" and a blast furnace simulator. The system predicts blast furnace performance by combining the partial unsteady simulator of the physical modeling method and the LOM of the local modeling method and supports the operation. To construct the system, the Java-based partial unsteady simulator is developed and the existing LOM is rebuilt by using versatile database and Java to realize the generalized LOM with general versatility. These systems are integrated by using Java.