Breeding method of practical bombyx mori strain with high tolerance to bombyx mori blood-type pyosis

The invention discloses a breeding method of a practical silkworm strain with strong tolerance to bombyx mori blood-type sepsis, which comprises the following steps: hybridizing a practical silkworm variety and an anti-BmNPV variety R to obtain an F1 subculture, feeding the F1 for selfing to obtain a B1 generation, feeding newly-hatched silkworms of the B1 generation to feed BmNPV viruses, selfing survived individuals to obtain a B2 generation, feeding the B2 generation for resistance detection, and reserving moth area selfing to obtain a B3 generation. The B3 generation is subjected to resistance test cross detection to obtain a B4 generation, the B4 generation is subjected to resistance determination selfing to obtain a B5 generation, the B5 generation selfing to obtain a B6 generation, the B6 generation is subjected to newly-hatched silkworm poison adding resistance detection and survival individual selfing to obtain a B7 generation, the B7 generation is subjected to LC50 value determination, the strain wi