The second largest desert of the world is:

The Arabian Desert is generally considered to be the second-largest hot subtropical desert in the world, covering an area of approximately 900,000 to 1,000,000 square miles (2.3 to 2.6 million square kilometers) in the Arabian Peninsula. However, if one takes into account the polar deserts, then it becomes the fifth largest desert in the world because the Arctic and Antarctic deserts are much larger.