Based on the NaSh model, the rules of straight movement and lane change are defined while considering the change of driving behavior under the guidance of traffic signs at ramp; besides, a traffic model with sensitive lane change under the cellular automation is proposed. Furthermore, computer numerical simulation result indicates that the procedure of sensitive lane change can effectively reduce the lane change ratio of the straight moving vehicles, thus obviously it has an inhibitory effect on unnecessary lane change; what is more, the longer the sensitive lane change zone, the more effective the inhibitory function is. However, the traffic signs at ramp cannot be set as far as possible. Lower the lane change ratio is, shorter the sensitive lane change zone needed is. The traffic signs at ramp are set with proper distance according to the lane change ratio can effectively increase systematic traffic flow as well as the critical entrance probability.