Lane changing manoeuvers is an essential rudiment in vehicle driving and has a significant impact on the characteristics of traffic flow. In the case of traditional cars, the driver operates the vehicle to complete the lane change whilst for autonomous vehicles, completing the lane change requires planning the lane change trajectory and controlling the vehicle speed during the lane change. Unreasonable lane change trajectory and vehicle speed may cause the vehicle to lose stability, threaten driving safety, increase energy consumption and waste energy. This paper considers the safety and economy of the lane changing process, and proposes a new lane changing method for vehicles. Firstly, use the existing virtual driving scene model in the laboratory to connect to the virtual driving instrument and use Unity3D to collect the driver’s lane-changing trajectory data, compare and analyze the lane-changing time and longitudinal average speed of different vehicles, establish the vehicle lane-changing trajectory model, and based on the obtained lane change the trajectory model is used to plan the lane change trajectory route. Then optimize the lane-changing trajectory model by adding constraints, and use the quadratic programming algorithm to make the lane-changing model more accurate. Secondly, when a vehicle needs to perform a lane-changing task, based on the vehicle dynamics model and the lane-changing model, a dynamic programming algorithm is used to plan the speed of the vehicle during the lane-changing process to achieve the optimal decision, mainly by taking the curvature of any point on the lane-changing trajectory as The disturbance is introduced into the calculation to discretize the curvature of the lane-changing trajectory at any stage k, so as to obtain a safe and economical vehicle speed trajectory during the lane-changing process. After the vehicle speed planning proposed in this paper, the fuel economy can be greatly improved, which can save about 7.63% of fuel and reduce the fuel consumption rate by 12.5%. Eventually, driverless cars will change lanes as needed to ensure lane-changing efficiency and safety while improving fuel economy. The research in this article provides a certain reference for the planning of vehicle lane change.