The invention discloses a method for detecting the bottom height of a hot metal ladle, and an implementation system of the method. The implementation system is composed of a car alignment detection switch, a ladle number detection device, a hot metal ladle bottom detection device, a hot metal ladle database and a data processing system. The method comprises the following steps: after the car-mounted hot metal ladle is aligned at a tap hole, the car alignment detection switch detects that a hot metal bottle car is in place; the ladle number detection device detects a ladle number; the hot metalladle bottom detection device mounted on the ground of the tap hole obtains the position of a bottom shell of each aligned car-mounted hot metal ladle; and the data processing system calculates the bottom height of the hot metal ladle through the distance between the bottom of the hot metal ladle and the bottom shell, recorded in the hot metal ladle database. The difficult problem of inaccurate detection of the bottom of the hot metal ladle due to dynamic change in an iron loading process is solved.