Abstract: Objective The drilling of ultra-deep wells over 10,000 meters in the oil and gas industry has gradually become a reality, and there is a great demand for weighting agents in ultra-high density drilling fluids. To recover the solid phase of weighting agents contained in the returned waste drilling fluid, save costs while treating solid waste and protecting the environment, Method the ‘clean gel breaking + high-speed water washing’ process is utilized to enrich barite in the waste drilling fluid. Subsequently, the reverse flotation method is adopted to remove the useless solid phase. The corresponding recovery process is designed and optimized. Results At the conditions of a solid-liquid ratio of 1∶2, a rotational speed of 1,000 r/min, and a single addition of the cleaning gel breaker YJ-1 at 5‰, high-quality barite with a density of 4.127 g/cm³ can be obtained. By adopting the "one coarse, two fine and one sweep" flotation process, with the collector sodium dodecyl sulfate dosage of 700 g/t and the food gel-type inhibitor gellan gum dosage of 700 g/t, a barite mixed concentrate with a comprehensive recovery rate of 81.86%, a comprehensive grade of ≥ 92%, and a mixed concentrate density of ≥4.2 g/cm³ can be obtained. Conclusion The method is characterized by clean pharmaceuticals, simple process and excellent quality of recovered barite, which may provide some ideas for the reuse of barite from waste drilling fluids in the oil and gas field wells.