The invention discloses a biological compost processing method of oil-based drilling wastes. The method comprises the following steps: screening strains capable of efficiently degrading petroleum hydrocarbons from the oil-based drilling wastes, and carrying out orthogonal experiment to prepare a solid compounded inoculant; adding the solid compounded inoculant into the oil-based drilling wastes, adding rice chaff as a supporter, and uniformly mixing to obtain compost of the oil-based drilling wastes; and adjusting the carbon/nitrogen ratio and the water content of the compost, turning, and carrying out sampling analysis to complete onsite composting. The degradation rate of total petroleum hydrocarbons in the oil-based drilling wastes reaches above 80% 1 month after the method is used to process the oil-based drilling wastes; and compost obtained in the invention can be used for planting plants, and the growth vigor of the plants is good within 3 months. The method has the advantages of simple process, simple required capital construction facility, handy enforcement surrounding a well site, short cycle, easy control, high degradation efficiency of the oil-based drilling wastes, low processing cost, and solving of troubles in economy and environmental protection for efficient exploitation of oil and gas fields.