Based on the WWH and SDNS cellular automata （CA） traffic model, an improved single lane traffic CA model with consideration of the change of driving rules is proposed. The model considers the drivers adopting different driving rules under mutative traffic condition, and introduces the rules of driving method change. Numerical simulations have been carried out. The results show the complicated evolution process of traffic flow. Different values of change probability have different effect on mixed traffic flow. With the increase of change probability, aggressive vehicles cause greater effect. In the evolution process, the change frequency can be controlled by the definition of the change probability and safety probability. The traffic flow is higher in the new model than in the NS and SDNS model. This proves that the stop status of the whole traffic flow has been improved.