1, steam ironing, stretching its fibers with both hands while it is hot. The fiber can't be stretched much at a time, so it needs to be heated and stretched repeatedly.

2. Cut the thick cardboard into the original size and shape, put the sweater on the cardboard, fix the bottom with several clothes pegs, and then steam iron the sweater repeatedly with an electric iron.

Take the clothes to the dry cleaner, dry clean them first, and find a special shelf of the same model as the clothes. After high temperature steam treatment, it can be recovered slightly.