The invention relates to an environment-friendly and coal-saving combustion improver for a power station and a preparation method thereof. The combustion-supporting agent is emulsified slurry preparedby mixing an oxidant, a surfactant, a catalyst and a corrosion inhibitor, wherein oil field drilling waste liquid and/or oil-containing sludge are/is added into the emulsified slurry. According to the environment-friendly and coal-saving combustion improver provided by the invention, the difficult-to-treat oil-containing sludge of an oil field and the drilling waste liquid are used as main raw materials and comprehensive utilization of wastes can be realized. The coal-saving combustion improver provided by the invention can promote uniform dispersion of a dispersion phase and also can be usedfor effectively improving the hydrophilicity of coal, improving the combustion efficiency and reducing the emission of sulfur dioxide and nitrogen oxide; the prepared coal-saving combustion improverhas low viscosity, high flowability and high stability; the coal-saving combustion improver obtained by the invention is an efficient coal-saving additive suitable for an industrial boiler and can beadded into direct combustion of fire coal of various power stations and industrial boilers.