One key step for silk protein further uses is to let them be dissolved in aqueous solution. However, the silk protein is usually not soluble in aqueous solution. Silk protein dissolved in calcium chloride solution is one of the few effective ways. Silk fibroin was well dissolved in 15-20min. in boiling calcium chloride solution [50% (w/v)] with the ratio of 15g dry waste silk per100mL calcium chloride solution. After dialysis, silk protein calcium salt unexpectedly showed excellent emulsification capacity and stability. Only 0.8-1.2% of silk protein calcium salt solution (50mL) could let 50mL soybean salad oil be mixed and emulsified well. Silk protein calcium salt may be used as a new protein-based surfactant.