The invention relates to a streptomyces composition preventing and treating potato scab and application thereof, belonging to the field of prevention and treatment of agricultural microorganisms and plant diseases. The composition provided by the invention comprises streptomyces anulatus CGMCC No. 15826 and streptomyces pratensis CGMCC No. 15829. If the seed potato is soaked in the composition, 98.47% of potato scab is prevented; if the composition is spread along a ditch, 97.15% of potato scab is prevented, so that the composition plays a synergic role, can effectively prevent potato scab, and has a good prospect of development and application.