Currently, great attention is being paid to the utilization of biomass, such as feather keratins. It is imperative to extract and dissolve keratins from animal keratinous materials for exploitation of innovative biopolymers. However, most of the current processes are based on strong acid and alkali hydrolysis, chemical cleavage and other violent reactions, which are not eco-friendly and/or result in severe degradation and destruction of feather keratins. In this study, high density steam flash-explosion (HDSF) as an innovative pretreatment of biomass was firstly employed to treat feather waste. In HDSF treatment, steam with a powerful seepage force first penetrates into fibrous tissues and cells of feathers, and then quickly expands and breaks free of the structure upon an explosive decompression at supersonic speed (within 0.0875 s). HDSF effectively destabilized β-sheet crystals and intermolecular disulfide bonds without causing substantial damage to the keratin protein chain, dramatically increasing the extraction and dissolubility of feather keratins in polar solvents like water, salt solution and weak bases, as well as enzymatic accessibility. HDSF treatment could be a sustainable and practical pretreatment for extraction of feather keratin for exploitation of biomaterials and conversion of feathers to nutrient animal feed instead of the current chemical hydrolysis and hydrothermal treatment.