Bio-cementation, or microbially induced calcite precipitation (MICP), has been shown to mitigate sand erosion; however, only few studies have used it on loess. This study used MICP to investigate the effects of this technology on the improvement of the surface erosion resistance of a loess-slope. Polyvinyl acetate (PVAc) was added to the cementation solution to further increase slope stability. The obtained results showed that MICP treatment resulted in an improvement of erosion resistance and treatment with 6 L/m2 of mixed solution achieved the best erosion control and highest surface strength. However, the loss of soil in MICP treated slopes still remained large. After adding PVAc to the cementation solution, the stability of the loess-slope increased significantly and resulted in less soil loss and increased surface strength. With 60 g/L PVAc, the surface strength of the slope decreased compared with 40 g/L PVAc because of the thinner depth of cementation. The high erosion resistance of the slope with added PVAc could be attributed to (1) the stable spatial structure of precipitation, and (2) the stronger resistance to tension or shear force from PVAc. These results demonstrated that MICP-PVAc treatment significantly mitigated surface erosion of loess-slopes, which presents promising potential for application in the field.