Coupling inductor and interleaved direct-current (DC) converter

The invention provides a coupling inductor and an interleaved direct-current (DC) converter. The coupling inductor comprises a magnetic core and M windings, wherein the magnetic core comprises a first end unit, a second end unit and low magnetizers, the first end unit comprises a first substrate and M first magnetic columns that protrude from the first substrate, M is an integer that is larger than or equal to 2, the second end unit comprises a second substrate and M second magnetic columns that protrude from the second substrate and are in one-to-one correspondence to the M first magnetic columns, the M first magnetic columns and the M second magnetic columns are connected through the low magnetizers to form M combined magnetic columns, the first end unit further comprises at least one first external magnetic column that protrudes from the first substrate, a gap is reserved between each first external magnetic column among the at least one first external magnetic column and the second end unit, the at least one first external magnetic column is located on the outer side of the M first magnetic columns, and the M windings are arranged on the M combined magnetic columns respectively and the winding directions of all windings are the same. The coupling inductor and the interleaved DC converter can support power supply high-density miniaturization.