The invention provides a cable junction unit capable of making laying work easier, reducing heat ingress and increasing efficiency. The junction unit is used between a first superconduction power delivery cable (i.e. a first cable) and a second superconduction power delivery cable (i.e. a second cable); the first and the second cable each at least has a first conduit for accommodating the superconductor and a second conduit disposed outside the first conduit; a heat insulation is performed between the first and the second conduit by vacuum; a support apparatus used for supporting the first and the second conduit radially is disposed between the first and the second conduit; the junction unit is connected with the first cable by a corrugated pipe cable having an inner and an outer corrugated pipe; the junction unit has a second conduit unit used for accommodating the first conduit unit which is connected with the first cable by the inner corrugated pipe; the second conduit unit of the junction unit is connected with a cable fixing part by an outer corrugated pipe with a variable-length and vacuum exhausting function; the inner corrugated pipe is connected with the first conduit located in the cable fixing part to compose a connection part with the first cable.