There are several ways to keep cats away from your Christmas tree. One way is to use a spray bottle filled with water and spray it on the cat every time it gets near the tree. Another way is to put aluminum foil on the bottom of the tree, which will scare the cat away. You can also try placing the tree in a room that the cat doesn't have access to. If all else fails, you can consider getting a pet fence or a repellent spray to keep the cat out of the tree.