A method, a device and an apparatus for planning a vehicle speed are provided. The method includes: determining initial planning speeds at a target path point and a reference path point based on curvature radiuses of a target front road and a reference front road, such that first and second lateral accelerations are not greater than a lateral acceleration threshold; and determining a target longitudinal acceleration and a target planning speed at the target path point based on the initial planning speeds at the target path point and the reference path point and a reference journey, such that the target longitudinal acceleration is in a defined range. Therefore, a vehicle can drive based on the target planning speed and the target longitudinal acceleration at the target path point, thereby avoiding drastic deceleration and lateral offset, improving driving safety of the vehicle and riding comfort and saving energy.