Methods to prevent cats from scratching furniture:
1. Regularly trimming a cat's nails is beneficial. If a cat's nails are trimmed in time, their destructive behavior will be greatly reduced.
2. Purchase at least one scratching post for your cat. Scratching posts are a way to discourage cats from scratching furniture, but owners may need to spend time encouraging their cats to use them. Make sure the scratching post is secured in one place so it doesn't wobble while the cat is scratching. Also, make sure the scratching post isn't too heavy or too high, otherwise it might fall and injure the cat.
3. Applying cat scratch tape to furniture will discourage cats from scratching. Cat scratch tape is very useful for making furniture unpopular with cats. Felines are very sensitive to texture, especially on their paws.
4. You can use a towel dipped in diluted disinfectant to wipe the furniture, and then spray it with cat repellent. Cat repellent is harmless to cats, but it can emit a smell that cats dislike, such as citrus, so the cats will naturally stay away from the furniture. 
Reasons why cats scratch furniture:
1. Cats have a need for self-exercise. Sometimes, cats scratch to stretch their muscles, perhaps because they've been sleeping too long or have been in the same position for too long. Scratching is a way for cats to relax.
2. Marking territory. Cats have numerous glands on their paws that secrete a sticky, scented liquid. This liquid adheres to the surface of the object being scratched, leaving a scent to mark their territory. The scent of this sticky liquid will attract the cat to return to the same spot to scratch again, and marking a new place makes the cat feel secure.
