Plant protoplasts are viable naked cells without cell wall and coated by cell membranes. They have all the characteristics of living cells and are ideal materials for basic life science research and crop breeding improvement.In this study, the leaves of potato Chunshu 4 tissue culture seedlings were used as explants, the isolation and purification conditions of Chunshu 4 protoplasts were explored and optimized. The results showed that MS medium containing 3 mg/L silver nitrate for 21 days could significantly increase leaf area and provide sufficient materials for protoplast preparation. When 0.4% cellulase + 0.5% pectinase + 0.1% isolating enzyme were used to hydrolyze leaves for 14 h under the condition of rotating speed of 35 rpm, 25 ℃ and darkness, the yield of protoplast was higher and the quality was the best. The protoplast was purified by interface method, and the protoplast size was the same, and there were few broken cells. The activity of protoplast prepared by the above method is over 90%, which can be used for protoplast culture.