Abstract: In recent years, the research and application of biodegradable materials have attracted great attentions of researchers. As a renewable and abundant resource, peanut protein isolate has various advantages, such as high biocompatibility, biodegradability, and processability. Therefore, it has been applied widely in food industry, agriculture, biological science, and biotechnology. Electrospinning technology has become one of the simplest and most effective methods to directly and continuously prepare nanofibers, and its operation mode is gentle. Meanwhile, electrospun nanofibers have many advantages such as high porosity, high specific surface area, high gas permeability, and small fiber pore size. In the food industry, on the one hand, nanofibers prepared by electrospinning technology can be used as a delivery system for some biologically active substances (e.g., natural polyphenols, enzymes, etc.) to enhance their performance in food processing and stabilities and bioactivities in the body. On the other hand, the nano-antibacterial film prepared by electrospinning technology can effectively inhibit spoilage bacteria on the food surface, thereby extending the shelf life of the food. To provide technical basis for the preparation of electrospun nanofibers of peanut protein isolate, in this study, peanut protein isolate (PPI) and polylactic acid (PLLA) was mixed at a mass ratio of 1:1 to prepare a blended solution, and the mass concentration of the blended solution (0.06-0.14 g/mL) on the properties of the blended solution and the morphology of electrospun nanofibers were analyzed. The best mass concentration of blending solution was determined by measuring the properties of the blended solution (conductivity, surface tension, and apparent viscosity, etc), characterizing the microstructure of the electrospun nanofibers with a scanning electron microscope (SEM), and calculate the fiber diameter using Image Plus Pro 6 software. The results showed that for the blended solutions with different mass concentrations, the surface tension was in the range of 16.81-18.31 mN/m. As the mass concentration of the blended solution increased, the conductivity decreased significantly (P< 0.05), the apparent viscosity increased (P< 0.05), and the fiber diameter gradually increased. When the mass concentration of the blended solution was lower than 0.10 g/mL, the fiber cannot be fully drawn, indicating that the fibrillation was poor. Meanwhile, beads were formed between adjacent fibers and adhesion occurred. When the mass concentration of the blend solution was greater than 0.10 g/mL, the prepared electrospun nanofibers had a relatively uniform diameter and a good morphology. This research achieved the manufacture of peanut protein isolate nanofibers, providing a basis for its application in food, biomedicine, and other fields.