From The Chronicles of Narnia Wiki

The Chronicles of Narnia is the collective name for C.S. Lewis' seven fatasy books relating to the World of Narnia. They were meant to be read in the order they were published, however they were not published chronologically, therefore there are two different views on their correct order:

[edit] Order of Publication

1. The Lion, the Witch, and the Wardrobe
2. Prince Caspian: The Return to Narnia
3. The Voyage of the Dawn Treader
4. The Silver Chair
5. The Horse and His Boy
6. The Magician's Nephew
7. The Last Battle

[edit] Chronological Order

1. The Magician's Nephew
2. The Lion, the Witch, and the Wardrobe
3. The Horse and His Boy
4. Prince Caspian: The Return to Narnia
5. The Voyage of the Dawn Treader
6. The Silver Chair
7. The Last Battle