The invention discloses reactor for removing organic matters from drinking water. The reactor comprises a water storage tank, and a sand filtering tank. In the sand filter tank, a material filtering layer, a bearing layer, a water distribution area, and a water discharge area are orderly arranged from top to bottom. The reactor also comprises an ozone contacting system, which is arranged between the water storage tank and the sand filter tank, a bioactive carbon processing area arranged in the sand filtering tank, and a backwashing system, which is connected to the bioactive carbon processing area. The reactor provides an environment, which is beneficial for the growth of biomembrane, and the biological degradation effect of microbes can be fully exerted, so the organic matters in drinking water can be eliminated. Moreover, the reactor is provided with a simple structure, thus the reactor can be easily applied to construction of new water plant, the effect is prominent, and the operation management is convenient.