The effects of different amounts of biochar（mass ratio: 0, 0.3%, 0.5%, 0.7%, 0.9%） on the growth and development of potato virus-free plantlet ‘Shapoti’and ‘Yanshu 4’were studied using peat vermiculite volume ratio of 2∶1. The results showed that biochar effectively promoted the root activity and agronomic traits of the two strains of virus-free seedlings, which made the virus-free seedlings grow well. Biochar treatment significantly improved the yield and quality of virus-free seedlings, and the yield increased first and then decreased. When the biochar application rate was 0.5% and 0.3%, the yields of ‘Xiaboti’and ‘Yanshu 4’were increased by 39.3% and 24.4%, respectively, and the starch content increased by 16.4% and 13.8%, respectively.