The average weight of adult purple finch is about 14g, the body length is about 14cm, and the tail is relatively long, accounting for half of the body length. This kind of bird is very beautiful both in character and appearance.

The head, throat, back and wings of finches decorated with purple-blue are dark chestnut, while the face, chest and abdomen are purple-blue, and the male even appears bright cobalt. The tail is very long (about 6.5 cm long). The beak is pink.

Their males and females can be distinguished from each other in appearance. The border of the dark chestnut area of the female bird is blurred, and the spots on the face, lower chest and abdomen are bright lavender blue, almost white. Young birds and adult birds are similar in color, but there are no colored patches, and their mouths are black. At about ten weeks old, young birds will partially shed their hair. The female bird will turn almost white, and the feathers around the male bird's eyes will turn blue and purple. Until they are five months old, they will completely shed their feathers and become the feathers of adult birds.