The invention discloses a combined insulated lead for switch cabinet power-frequency and alternating-current withstand voltage test, comprising a plurality of insulated leads, two wiring clamps used for being respectively and electrically connected with a tested object and a test transformer, and a plurality of two-way joints used for connecting two insulated leads. Each of the insulated leads is provided with a bare metal connection peg at each of the two ends. The rear end of at least one metal handle of each wiring clamp is provided with a jack in tight fit with the connection pegs of the insulated leads. The middle of each two-way joint is a metal conductive column, the two ends of the metal conductive column are respectively provided with a jack in tight fit with the connection pegs of the insulated leads, the metal conductive column is coated with an insulating layer, and the insulating layer extends to the outer ends of the jacks to form ladder-shaped holes for the insulating layer parts of the insulated leads to be embedded in. The insulated leads and the two-way joints are provided with external insulation and are not restricted by space and environment, other field electrical equipment does not need to be moved, and the testing efficiency and safety performance can be improved. The combined insulated lead can be assembled and disassembled freely as needed, and is convenient to operate and easy to carry.