A system for detecting a vehicle speed, includes: a pulse ring including a pulse ring rotation part rotating according to travel of a vehicle, and a plurality of pitch units provided in the pulse ring rotation part at a predetermined interval; a vehicle speed sensor adjacently provided to the pulse ring and configured to output a voltage signal generated according to a distance between the vehicle speed sensor and a pitch unit; an output unit configured to output a voltage pulse signal and a voltage pulse amplitude change signal of the vehicle speed sensor; a first vehicle speed detection unit configured to detect the vehicle speed based on the voltage pulse signal of the output unit; and a second vehicle speed detection unit configured to detect the vehicle speed based on the voltage pulse amplitude change signal of the output unit, in which at least one of the plurality of pitch units has an adjacent distance which is different from an adjacent distance between another of the pitch units and the vehicle speed sensor.