KVM switch

A KVM switch with an expansion module slot is disclosed. The KVM switch comprises a housing, a printed circuit board and an expansion module slot. The housing includes a receiving space, a panel disposed at a side thereof and a removable back panel disposed at another side thereof. The printed circuit is disposed in the receiving space, and comprises a controller, a switching circuit, a plurality of connectors and a plurality of wires. The expansion module slot is disposed corresponding to the back panel and is used for receiving an expansion module.