Rhamnolipid, a widely used biosurfactant, is produced by Pseudomonas aeruginosa, but the overall production cannot fulfill the demand of industrial use. BNDS China 2021 aims to increase rhamnolipids production using directed evolution and protein scaffold. For the convenience of genetic engineering, rhlA, B, and C which are endogenous enzymes in P.a. are transformed into E. coli. With the EvolvR directed evolution system, random mutations can be added to the gene and variants with higher activity can be screened with a rhamnose induced promoter fused with antibiotic resistance genes and the rhamnolipidases that can hydrolyze rhamnolipid into rhamnose. Protein scaffold, which can fuse the separate enzymes into a complex, is also included in our design in order to reduce the shunt product and increase the yield. Two Mathematical models are designed to quantyitatively validate our biosensor for EvolvR system,and to increase the activity of the enzyme by point mutation.