The content of flavonoids in silkworm and its silk was determined using NaNO₂-Al(NO3)₃- NaOH colorimetry. The results showed that?the flavonoid content in cocoon layers?of green silkworm?variety was five times higher than that in yellow and purple?fluorescent?color?silkworms?and no difference in flavonoid?content was observed in ?cocoon layers? of yellow and purple silkworm varieties. The content of flavonoids in cocoon pupas of green cocoon variety was equivalent to that of purple?fluorescent?color silkworm, but was 1.3 times higher than that in cocoon pupas of the yellow fluorescent?color?silkworm. The content of flavonoids in three varieties of silkworm pupasare was significantly higher than that in cocoon layers.