Simulation tools are widely used for performance evaluation of newly proposed systems. However, many industrial simulation projects fail to attain the original goals ,especially when very complicated decision logics of the experienced operatorsare needed to be modeled. We propose a technique to overcome the oabstacles. In the proposed technique, complicated decision logics are not directly modeled but an interface for interactive input is provided in the model. While running the simulation model in concurrent animation mode, whenever operator's decisions are needed an interfce screen is displayed for operator's decisions. The operator then makes decisions using the information which is provided by the animation proces itself. This technique was successfully applied to an industrial simulation projects in which alternatives were evaluated for increasingthe color lot size of car print shop.