The present invention discloses an expansion dock including a base, a socket, an expansion platform and a driving mechanism. The socket is installed on a side of the base and pivoted to the base. A portable electronic device can be inserted into the socket. The expansion platform is installed inside the base and protrudable from the side of the base. The driving mechanism drives the expansion platform to protrude from the side of the base as the portable electronic device is inserted into the socket and pivoted to a predetermined angle relative to the base.