The invention provides a main wiring system of a medium-voltage power distribution cabinet. The main wiring system comprises a metering cabinet, a PT cabinet, an incoming cabinet and a feeder cabinet, wherein the metering cabinet comprises a first current transformer, a first fuse, a metering voltage transformer, a first charged display and a first arrester; an incoming line terminal of the metering voltage transformer sequentially passes through the first fuse and the first current transformer and is connected with a medium-voltage bus; an outgoing line terminal of the first current transformer sequentially passes through the first charged display and the first arrester and is grounded; the PT cabinet comprises a three-winding voltage transformer and a second fuse; the incoming line terminal of the three-winding voltage transformer passes through the second fuse and is connected with the medium-voltage bus; the incoming line terminal of the second fuse passes through a second arrester and is grounded. The main wiring system of the medium-voltage power distribution cabinet is simple in structure and convenient to use; the fault rate of the system is reduced; the electric energy quality is improved; the power reliability is ensured; the electric cost expenditure is reduced; and the reliability of a power distribution network is improved.