The invention discloses a high-precision rotary horizontal working table which comprises a working table, a working table supporting seat, a working table center shaft, a large belt pulley, a rotating shaft, a small belt pulley, a circular foundation plate, a support, an auxiliary base and a deflection angle assembly, the working table center shaft is located below the working table, and the large belt pulley is installed on the working table center shaft; the rotating shaft is located below the rotating disc, the small belt pulley is installed on the rotating shaft, the deflection angle assembly is arranged above the rotating disc, and the rotating disc, the small belt pulley and the rotating shaft rotate around the center line of the rotating shaft together. And the circular foundation plate is provided with a foundation plate center through hole through which the rotating shaft passes and a plurality of foundation plate reference pin holes which are uniformly distributed on a concentric circle. According to the high-precision rotary horizontal workbench, the structure is adopted, the high-precision deflection angle is achieved through the deflection angle assembly, the accuracy of the deflection angle of the horizontal workbench is further improved through belt transmission, and therefore the machining precision is guaranteed, and the manufacturing cost is reduced.