The invention discloses a water leakage detection device of a valve tower of a converter valve. The water leakage detection device comprises a water leakage collection tray, wherein the upper surface of the water leakage collection tray is provided with a water leakage collection place; a water leakage detection cylinder is fixed at the collection place of the water leakage collection tray; a water inlet is arranged on the water leakage detection cylinder; two light transmitting optical cables and two light receiving optical cables are respectively and correspondingly fixed at two sides of the water leakage detection cylinder; a floating block is arranged in the water leakage detection cylinder; a baffle for blocking optical signals from the light transmitting optical cables is fixed on the upper end face of the floating block; two holes, namely a first long hole and a second long hole, respectively for the optical signals of the two light transmitting optical cables to pass through, are arranged at the upper end part of the baffle; and lower edges of the first long hole and the second long hole are used for moving to respective corresponding optical cables successively in the raising process of the floating block. The water leakage detection device disclosed by the invention is capable of accurately detecting different water leakage conditions of the valve tower, thus, the operation of the valve tower can be effectively protected.