The invention discloses a petroleum degrading bacterium as well as a preparation method and an application thereof. The preparation method comprises the following steps: uniformly mixing polyving akohol and sodium alginate solution at a certain ratio, adding with activated carbon, uniformly mixing, cooling, and adding petroleum degrading bacterium solution into the cooled mixture according to the ratio of the cooled mixture to petroleum degrading bacterium solution being 10 to 1, wherein the petroleum degrading bacterium solution contains flavobacterium indologenes, caulobacter, achromobacter and burkholderia cenocepacia at the weight ratio of 36 to 22, to 18 to 5; dropwise adding the mixed solution into calcium chloride saturated boric acid solution through an injection syringe for balling; and standing, taking out microspheres in the solution, washing by adopting sterilized 0.9% NaCl solution, and thus obtaining the solid microspherical petroleum degrading bacterium. The petroleum degrading bacterium can be used for restoring petroleum polluted soil, the solid petroleum degrading bacterium is convenient to transport and store; and technical support is provided for the practical application of restoring the petroleum polluted soil by microorganisms.