To keep cats away from a fake Christmas tree, you can use a few different methods. One option is to spray the tree with a cat repellent spray or sprinkle catnip around the base of the tree. This will help deter the cats from getting too close to the tree. Additionally, you can try placing a few boxes or other obstacles around the base of the tree to create a physical barrier that the cats cannot easily cross. Finally, if you are feeling a bit crafty, you could create some homemade cat toys that are specifically designed to keep them occupied and away from the tree.