The invention discloses a motor system for a vehicle, a control method and the vehicle, and relates to the technical field of vehicles. The motor system for the vehicle comprises a motor, and the motor comprises a motor output shaft, wherein the motor shaft is provided with at least one spline. The system also comprises a speed reducer spline shaft sleeve which covers the outer part of the motor output shaft and is matched with a spline of the motor output shaft through a key groove, wherein at least part of the splines are internally provided with movable buffering sliding blocks, and the buffering sliding blocks are configured to be controlled to stretch out of the splines in the torque reversing process of the motor and make contact with the inner walls of the key grooves before the splines make contact with the inner walls of the key grooves so as to buffer the contact between the splines and the key groove. The invention further provides a corresponding control method. Meanwhile,the invention further provides the vehicle which comprises the motor system. The silence and comfort of the passenger compartment and the dynamic response of the motor can be considered at the same time.