The invention discloses an efficient acidic oil sludge decomposing agent, comprising the following component materials in percentages by weight: 1-15% of oxidant, 1-10% of coprecipitator, 5-30% of flocculating agent, 1-10% of surfactant, 0.5-10% of emulsion breaker, 1-10% of acidity regulator and 50-90% of water. The invention further discloses a preparation method of the efficient acidic oil sludge decomposing agent. The preparation method comprises the following steps of: 1, preparing sodium carboxymethylcellulose hydrosol; 2, dissolving all kinds of component materials; and 3, adding the sodium carboxymethylcellulose hydrosol prepared in the first step into the solution obtained in the second step so as to obtain the efficient acidic oil sludge decomposing agent. The invention further discloses application of the efficient acidic oil sludge decomposing agent. The efficient acidic oil sludge decomposing agent disclosed by the invention has the advantages of simple preparation process, low cost and easy industrialization; by means of chemical reaction, surface activation action, flocculation and salting-out emulsion breaking actions, the viscosity of the oil sludge is reduced, the oil phase, the water phase and the sludge phase are effectively separated, and the efficient acidic oil sludge decomposing agent can be used for recovering the crude oil from the oil sludge and quickly treating the petroleum pollution soil.