Abstract: In order to improve the driving range of pure electric vehicles, this paper proposes an economical cruise speed planning and control method. According to the driving environment of a vehicle, such as the following mode or the cruise mode, a short-term speed planning method based on long short-term memory (LSTM) and a long-term speed planning method based on genetic algorithm (GA) are proposed respectively. The economical cruise control system is designed based on a hierarchical structure, in which the upper layer obtains the planned speed profile by constructing the objective function of the problem to be optimized and solving it with GA, and the lower layer takes the optimal speed curve as the input and realizes distance control and speed control based on the tracking controllers. The pure electric vehicle model and the economical cruise control system are built on the joint simulation platform of CarSim and Simulink. The research results show that the introduction of speed planning can provide the vehicle with the optimal speed curve after energy optimization in multiple scenarios so as to reduce the energy consumption of electric vehicles and improve travel efficiency.