Abstract: For the rapid preparation of strains of live influenza vaccine, it is important to have a rapid method for screening vaccine reassortants. In this paper, a method of pyrosequencing was used to analyze the genome of reassortants obtained by crossing the donor of attenuation B/Leningrad/14/17/55 and the wild-type virus B/Indiana/25/2015. It has been shown that pyrosequencing allows the composition of the reassortant genome to be evaluated quickly, economically, and with high accuracy.