The invention discloses a prevention method for tetra hybrid bombyx mori pebrine germ vertical transmission. The method comprises the following steps: for silkworm eggs which do not need to be subjected to cold storage treatment, enabling the silkworm eggs to stand for 15 to 30h at a temperature of 20 to 30 DEG C after bombyx mori lays the eggs, then carrying out immersion treatment for 6 to 10min in water with a temperature of 47 to 48 DEG C, taking out the silkworm eggs, then eluting the silkworm eggs with clear water stage by stage until the silkworm eggs are odorless after are, and carrying out hatching hastening after drying; for silkworm eggs subjected to cold storage treatment, taking the silkworm eggs out of a cold storage, protecting for hours at a temperature of 10 to 20 DEG C, carrying out immersion treatment in water with a temperature of 47 to 52 DEG C for 6 to 10min, taking out the silkworm eggs, then eluting the silkworm eggs with clear water stage by stage until the silkworm eggs are odorless, drying, and then carrying out hatching hastening. The method disclosed by the invention can inactivate 97 to 99% of tetra hybrid bombyx mori sporozoan pathogeny, reaches a relative control effect of 90 to 97% on bombyx mori pebrine germ vertical transmission, can reach silkworm egg hatchability of over 93%, and has no harmful effect on growth development of bombyx mori.