The invention relates to a rice growth regulator capable of regulating rice field water to be black, which is obtained though the technical processes of nitration degradation, neutralization salification, sedimentation, complexation, spray drying, extrusion granulation and the like by taking humic acid and rice hull ash as main raw materials. In the invention, the regulator is mainly used for regulating the accumulated temperature for the growth of rice in cold regions; and through regulating rice field water to be black, the yield increasing and the precocity of the rice in the cold regions are promoted by utilizing the method for raising the accumulated temperature in the growth period of the rice. The rice growth regulator has the advantages of no toxicity, no harm and no pollution, is an effective product for guaranteeing the yield and the income increasing of the rice in the cold regions, and is a more ideal rice growth regulator.