The invention discloses a vehicle speed calculation method, which comprises the following steps: acquiring the rounds of rotation Q1 of a left wheel of an automobile in a cycle time through a left half shaft rotation detection assembly; acquiring the rounds of rotation Q2 of a right wheel of the automobile in a cycle time through a left half shaft rotation detection assembly; acquiring the wheel speed V1 of the left wheel of the automobile according to the rounds of rotation Q1; acquiring the wheel speed V2 of the right wheel of the automobile according to the rounds of rotation Q2; comparingthe wheel speed V1 with the wheel speed V2; the vehicle speed value is equal to the larger value of the wheel speed V1 and the wheel speed V2 if the difference between the wheel speed V1 and the wheelspeed V2 is more than 25%-35% of the smaller value of the wheel speed V1 and the wheel speed V2; the vehicle speed value is equal to the average value of the wheel speed V1 and the wheel speed V2 ifthe difference between the wheel speed V1 and the wheel speed V2 is less than or equal to 25%-35% of the smaller value of the wheel speed V1 and the wheel speed V2. According to the vehicle speed calculation method, the vehicle speed is calculated through the rounds of rotation Q1 of the left wheel of the vehicle in the cycle time and the rounds of rotation Q2 of the right wheel of the vehicle inthe cycle time, so that the error caused by the inconsistency between the rotation speed of the output shaft of the gearbox and the rotation speed of the wheel is effectively avoided, and the accuracyof the vehicle speed calculation is improved.