The invention relates to a frequency-conversion horizontal cyclic loading test device and aims at providing the frequency-conversion horizontal cyclic loading test device which is simple in structure, low in cost, large in loading frequency and various in loading manner. According to the technical scheme, the frequency-conversion horizontal cyclic loading test device is provided with a model pile arranged in a water trough. The frequency-conversion horizontal cyclic loading test device is characterized in that a plurality of loading mechanism sets are connected to the model pile; each loading mechanism set is composed of a gravity loading mechanism and a moment loading mechanism, wherein the gravity loading mechanism and the moment loading mechanism are symmetrically connected to the two sides of the model pile; and each gravity loading mechanism is provided with a weight block I and a steel wire rope I, wherein one end of the steel wire rope I is connected to the model pile, the other end of the steel wire rope I is connected with the weight block I, the steel wire rope I is hung on a pulley I, and the pulley I is fixed to the ground through a connecting rod I and a rigid loading frame. The frequency-conversion horizontal cyclic loading test device is suitable for conducting long-period horizontal cyclic researches on an offshore single pile indoor model test.