The reciprocal feedback mechanisms between the knowledge rigidity and the enterprise internal activities, as well as the differences between firms in the dynamic trend of rigidity formation and evolution, are key issues to recognize and respond to this knowledge dependence phenomenon. The case of specific enterprise’s relying on existing business process in the information system is discussed in detail. Based on theoretical analysis of the formation and impact of knowledge rigidity, also the knowledge change decision in firms, this paper proposes a system dynamics model of the knowledge rigidity through the causal analysis of critical factors and the setting of functions and parameters. Simulation results of multi scenarios show that the knowledge rigidity phenomenon appears three stages in a single cycle. It emerges gradually at early stage, being stable continuously at mid-term and drops quickly at later stage. The utility reinforcing factor promotes the growth of rigidity, while external environmental factors are triggers of rigidity mutation. To enterprise with low base value of rigidity and high sense of change consciousness, its rigidity shows faster growth and deeper influence, but the duration is shorter. On the other hand, knowledge are replaced frequently, while more utilities are obtained. Firms should understand the chain reaction of the impact of knowledge rigidity caused by specific decision behavior. Then firms can control their over-dependence on existing knowledge by enhancing change consciousness or monitoring utility expectations, which help achieve rapid response to external environment changes.