In the non-platoon-vehicle lane-changing process, the distance that allows for avoiding a collision between the lane-changing vehicle and other vehicles is the minimum safe critical distance. However, the difference between platoon lane changing and non-platoon-vehicle lane changing is that the vehicles in the platoon can tolerate smaller safety distances because of their unique cooperative characteristics. Meanwhile, the distance should not be too large, which will lead to the dissolution of a platoon in the high-speed scene. Another way is to undertake platoon lane changing in dissolution. If the platoon is disbanded before or during the lane changing, the vehicles change lanes one by one according to the lane-changing gap of individual vehicles, and then all the vehicles form a platoon again. This method wastes the advantage of efficient transportation for a platoon, and the platoon cannot usually be reorganized after it is disbanded. Due to the high speed of vehicles on the highway, the state of the following vehicles and the leading vehicles will become greatly different over a short time; thus, it is difficult to realize platoon re-combination. Therefore, it is necessary to find a reasonable dynamic gap between platoon vehicles. Many studies use the safety potential field to characterize the spatial distribution of driving risk around vehicles in complex traffic environments. The safety potential field theory is applied to the safe distance between individual traffic participants to prevent collisions [17; 18; 19]. [PERSON] et al. [20; 21] demonstrated the objectivity and universality of the potential field in traffic from both macro and micro perspectives and calibrated the potential field car-following model using NGSIM (next-generation simulation) data. [PERSON] et al. [22; 23] established a unified model to characterize the \"driving risk field\" based on the previous research, put forward the concept of a \"driving risk field,\" and validated the model with real vehicles. The results show that the model can provide an effective method for evaluating the driving risk in a complex traffic environment. The field theory opens up a new perspective for traffic flow modeling. In our previous research, we took safe driving as the goal and established a lane-changing model for non-platoon vehicles based on the safety potential field in combination with the characteristics of real-time perception and sharing of vehicle speed, acceleration, and other information in the CAVs system [16; 24]. In this study, based on the original research, a new field model that is suitable for platoon lane changing was established. The dynamic gaps for different motion states were proposed. The contributions of this study are as follows:  
1. For the first time, a gravitational potential field was introduced to represent the traction between intra-platoon vehicles;
2. The gravitational potential field and repulsive potential field were unified into a system that is named the \"intra-platoon potential field\";
3. The concept and calculation method of a dynamic gap of safety interval for platoon lane changing was proposed;
4. The method framework of entire-platoon lane changing was proposed and related experiments were carried out. The remainder of this paper is organized as follows. First, the scenario description for platoon lane changing is defined in Section 2. Then, in Section 3, an intra-platoon potential field model is constructed and the potential field distribution of the vehicle under different motion states is analyzed in detail. According to the intra-platoon potential field model, the design of the platoon-lane-changing process and safety distance threshold model of avoiding crashes are given in Section 4. Section 5 presents the numerical simulation results and comparative verification, along with a discussion. Finally, the conclusions are summarized in Section 6.