Drivers affective states will transfer along with environmental changes during driving. The changes can affect directly drivers manipulation. The affective state is represented mainly as drivers propensity. It plays a significant role for researching the active driving and auto-driving systems to reveal the transformation mechanism of drivers propensity exactly in complex environment. Data of drivers propensity can be collected and analyzed through driving experiments in different two-lane environments from the angle of environmental change, especially evolution of vehicle group. It reveals transformation mechanism of drivers propensity under different environment conditions. Verification results show that the predictive outcomes which are gotten by transformation rule are consistent with that of real-time recognition. It also shows that the transformation mechanism revealed in this paper is scientific and reasonable.