A self-tuning apparatus of vehicle speed pulse coefficient and a method thereof wherein a vehicle speed pulse coefficient is flexibly adjusted by environments in which a mobile object travels and a current status of the mobile object to thereby enable to precisely calculate a travel distance and a travel speed of the mobile object in response to a vehicle speed pulse signal. A tuning start signal is generated when a value of DOP (Dilution of Precision) and travel status of the mobile object meet a condition for tuning a vehicle speed pulse coefficient value, and the vehicle speed pulse coefficient value is calculated by a travel speed pulse coefficient tuning unit using a travel distance of the mobile object discriminated by a discriminating unit and the number of vehicle speed pulse signals counted by a travel speed pulse signal counting unit during an established period of time when a tuning start signal is kept being generated during the established period of time, and the pre-established travel speed pulse coefficient value is tuned by the calculated vehicle speed pulse coefficient value.