Polyethylene terephthalate (PET), one of the most widely used plastics in the world, is currently causing serious environmental pollution. In recent years, more and more researchers have focused on the enzymatic degradation of PET, which is a more environmentally friendly degradation and recycling method than the traditional chemical and physical recycling methods. In this study, the team established an efficient secretion system of PET degradation enzyme in E. coli BL21(DE3) using the signal peptide PelB and the colistin-releasing protein Kil, which not only improved the enzyme yield but also greatly simplified the purification process of PET degradation enzyme. This provided a more convenient tool for further study of the enzyme. In addition, the team rationalized the PET hydrolase SbPETase from Schlegelella brevitalea sp. nov. and used the established secretion system to rapidly screen for triple mutants with significantly increased activity.