In order to analyze the comfort and safety of passenger cars changing lanes on double-arch road surface in the same direction, Carsim simulation software was used to establish the track model of passenger cars changing lanes, vehicle dynamics model, double-arch road models in the same direction and one-way slope road models. The limit radius of flat curve was taken as the track radius value of lane changing, and the cross-arch road changing test was carried out in multiple working conditions. And the accuracy of the simulation model was verified by the real car driving experiment. The changing state of passenger car on double-arch road in the same direction was analyzed according to the four indexes including lateral acceleration, yaw velocity, peak adhesion coefficient and lateral load transfer rate. The results show that the road type has a great influence on the stability of vehicle lane changing. According to the changes of evaluation index and return gain coefficient, the stability of SUV and Minivan lane changing can meet the requirements of safe driving under the condition of double-arch road surface in the same direction. The road types from high to low for lane change stability are as follows: one-way slope road > parabolic arch road > curved arch road; Under the condition of curved road arch, the stability of SUV is better than Minivan. Overspeed has a significant impact on the stability of passenger cars changing lanes. The higher the overspeed, the worse the stability, that is, when the basic speed is 100 km/h and 120 km/h, when the overspeed is 10% and 20%, there is no sidespoiling risk in the process of lane changing, but the vehicle stability is in a poor state.