An input/output switching system for a server is disclosed herein. The input/output switching system includes a logic-determination device and at least one connector. The at least one connector electrically connects with at least one electronic card. The at least one connector comprises at least one first standard-bus pin group, at least one second standard-bus pin group, and a first distinguishing-signal pin group. The logic-determination device generates a first determination result which is used for determination of type of the at least one electronic card by receiving a distinguishing signal transmitted from the first distinguishing-signal pin group.