A data switching circuit is provided. The circuit includes a control unit and a switching unit. The control unit provides a switching signal. The switching unit has N input ends and (N+1) output ends. The switching unit receives the switching signal. If N is an integer number and 1≦i≦N, the switching unit turns on both the connection between the i-th input end and the i-th output end and the connection between a dummy data and the (N+1) output end as the switching signal takes a first status. The switching unit turns on both the connection between another set of dummy data and the first output end and the connection between the i-th input end and the (i+1)-th output end as the switching signal takes a second status.