Christmas Laurel is the first Christians in Ancient Rome decorated their homes at the Saturnalia with laurel. Pagan Romans believed laurel was sacred to the sun god Apollo. When Romans became more Christian, laurel became a symbol of Christmas.
Laurel has been worn as a wreath on the head to symbolise success and victory for thousands of years. It symbolises the victory of God over the Devil. Wreaths at Christmas are typically made with Holly and Ivy for reasons cited above.
What I find even more intriguing is the circular shape of the wreath which speaks of cycles (wheels of time, seasons), infinity, immortality, inclusion, community and the unbreakable bonds we share with Nature and our Beliefs (faith).
The laurel represents victory or triumph, particularly over temptation and trial, because of the ancient practice of crowning the victor in a contest with a wreath of laurel. Because its leaves never wilt, it can may also symbolize eternity.