Heat exchanger network (HEN) is one of the major technique of energy saving. We have proposed a HEN design system using pinch technology and multiagent. In this system, the maximum heat recovery is derived from pinch technology. And then, an initial HEN can be obtained according to the AreaTargeting method in order to meet the maximum heat recovery. The initial HEN has complexity and a number of heat exchangers due to the AreaTargeting method. Therefore it is necessary to simplify the HEN without deterioration of the energy saving efficiency. In our system, simplification strategy is defined to prescribe the priority order of procedure and/or the part of HEN. The number and variety of resulted HENs increase along with the number of strategies. It is useful if a large number of HENs with wide variety is obtained because the preferable HEN must be different due to the process objectives or conditions. We implemented several HEN design agents (HENDAs) with different simplification strategies. In this study, we introduced several improvements in simplification strategy of HENDAs using strategy switching mechanism. Several HENDAs have their own strategy, and then they exchange the HENs on the way—that is “strategy switching” from the standpoint of a HEN. We investigated the effect of improvements in the simplification strategies and strategy switching mechanism.