It does not refer to a specific person.
The blue silk thread under the balcony comes from "Miscellaneous Songs and Songs: Willow Branches" by Zhang Hu, a poet of the Tang Dynasty. The meaning of this poem is: arranging clouds of black hair under the balcony. The word "green silk" in this poem is usually used to describe a woman's long hair, indicating a woman's beauty and tenderness.
This poem is a poem describing the beauty and tenderness of women. It comes from ancient poems, songs or folklore.