The invention discloses a brake rotor fixing mechanism and an installation method thereof. The mechanism comprises a stator fixed to an end cover of a motor through a bolt, and a rotor connected with a motor shaft in an integrally formed mode, wherein the stator and the rotor are coaxially installed, the rotor is located on the outer side of the stator, an axial gap is reserved between the stator and the rotor, the rotor comprises an armature, a leaf spring, a flange and a fastening ring, the armature is located on the outer side of the stator, the leaf spring is arranged between the outer side of the armature and the inner side of the flange, a flange boss on the outer side of the flange is connected with the motor shaft in a sleeving mode, an open groove is formed in the flange boss, and the fastening ring is connected to the flange boss in a sleeving mode to squeeze and deform the flange boss so as to clamp the motor shaft. According to the brake rotor fixing mechanism and the installation method thereof, axial movement is avoided, structure is simple, installation is easy, reliability is high, cost is low, the mechanism can be used under positive and negative impact and in a high-vibration environment, and application prospects are broad.