A sliding hinge for a portable electronic device has a stationary leaf, a link assembly, a main sliding leaf and a side sliding leaf. The linking assembly is mounted pivotally on the stationary leaf via a pivoting middle. The main and side sliding leaves are connected respectively to two ends of the linking assembly. With the linking assembly, the main and side sliding leaves are moved simultaneously. Therefore, when the portable electronic device is not used, the main and side sliding leaves fully overlap with the stationary leaf to achieve a smallest footprint. When the portable electronic device performs multiple functions, the main and side sliding leaves are slid out to reveal control buttons.