Because of the geographical features, tunnels play an important part in Taiwan. However, the law forbids lane-changing behavior when driving in the tunnel in Taiwan. If we understand the characteristic of driver behavior according to car-following theory, it will have been a great help to manage the tunnels. But the study about traffic flow in tunnel presently only focus on macroscopic analysis and they could not understand the change of reaction time and percipient level which influence driver behavior actually. Thought there are many papers study on microscopic car-following behavior or comparison analysis of different car-following model in the same traffic environment, they do not study the situation in tunnels. The research focuses on microscopic analysis and use simulation technology to understand the characteristic of driver behavior in different section of tunnel. The results from this research are: sensitivity factor in the exterior section is 1.5 times of the section in the tunnel. ABX and SDX are 20~55 m out of the tunnel and 23~60 m in the tunnel. CLDV and OPDV broaden when the cars drive into the tunnel deeply. Driver behavior conforms to the GM model in the entrance and middle of tunnel and is similar to the former vehicle. On the other hand, Driver behavior conforms to the psycho-physical model in the exit and initial section of tunnel. Driver behavior is responded according to their percipient level of relative velocity and distance to the former vehicle.