This paper modifies from Shackleton et al. (2004) to analyze the optimal switching strategy decision in a duopoly agent market. We introduce a commission rate. By the real options game approach, we derive the optimal switching strategy showing the equilibrium in the market. The results demonstrate that the agent with higher net growth rate and lower volatility is more likely to be the exclusive agent. In addition, under the conditions of high commission rate, high correlation coefficient of the net profitability volatility and high total switching costs, switching is less likely to appear. Moreover, we find out the hysteresis is not the factor to affect the switching probability.